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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<refentry id="re-drbdsetup">
  <refentryinfo>
    <date>5 Dec 2008</date>
    <productname>DRBD</productname>
    <productnumber>8.3.2</productnumber>
  </refentryinfo>
  <refmeta>
    <refentrytitle>drbdsetup</refentrytitle>
    <manvolnum>8</manvolnum>
    <refmiscinfo class="manual">System Administration</refmiscinfo>
  </refmeta>
  <refnamediv>
    <refname>drbdsetup</refname>
    <refpurpose>Setup tool for DRBD
    <indexterm significance="normal">
      <primary>drbdsetup</primary>
    </indexterm>
    </refpurpose>
  </refnamediv>
  <refsynopsisdiv>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">disk</arg>
      <arg choice="req" rep="norepeat">
        <replaceable>lower_dev</replaceable>
      </arg>
      <arg choice="req" rep="norepeat">
        <replaceable>meta_data_dev</replaceable>
      </arg>
      <arg choice="req" rep="norepeat">
        <replaceable>meta_data_index</replaceable>
      </arg>
      <arg choice="opt" rep="norepeat">-d<arg choice="req" rep="norepeat"><replaceable>size</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-e<arg choice="req" rep="norepeat"><replaceable>err_handler</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-f<arg choice="req" rep="norepeat"><replaceable>fencing_policy</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-b</arg>
      <arg choice="opt" rep="norepeat">-t<arg choice="req" rep="norepeat"><replaceable>disk_timeout</replaceable></arg></arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">net</arg>
      <arg choice="opt" rep="norepeat">
        <replaceable>af:</replaceable>
      </arg>
      <arg choice="req" rep="norepeat">
        <replaceable>local_addr</replaceable>
      </arg>
      <arg choice="opt" rep="norepeat">
        <replaceable>:port</replaceable>
      </arg>
      <arg choice="opt" rep="norepeat">
        <replaceable>af:</replaceable>
      </arg>
      <arg choice="req" rep="norepeat">
        <replaceable>remote_addr</replaceable>
      </arg>
      <arg choice="opt" rep="norepeat">
        <replaceable>:port</replaceable>
      </arg>
      <arg choice="req" rep="norepeat">
        <replaceable>protocol</replaceable>
      </arg>
      <arg choice="opt" rep="norepeat">-c<arg choice="req" rep="norepeat"><replaceable>time</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-i<arg choice="req" rep="norepeat"><replaceable>time</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-t<arg choice="req" rep="norepeat"><replaceable>val</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-S<arg choice="req" rep="norepeat"><replaceable>size</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-r<arg choice="req" rep="norepeat"><replaceable>size</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-k<arg choice="req" rep="norepeat"><replaceable>count</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-e<arg choice="req" rep="norepeat"><replaceable>max_epoch_size</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-b<arg choice="req" rep="norepeat"><replaceable>max_buffers</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-m</arg>
      <arg choice="opt" rep="norepeat">-a<arg choice="req" rep="norepeat"><replaceable>hash_alg</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-x<arg choice="req" rep="norepeat"><replaceable>shared_secret</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-A<arg choice="req" rep="norepeat"><replaceable>asb-0p-policy</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-B<arg choice="req" rep="norepeat"><replaceable>asb-1p-policy</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-C<arg choice="req" rep="norepeat"><replaceable>asb-2p-policy</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-D</arg>
      <arg choice="opt" rep="norepeat">-R<arg choice="req" rep="norepeat"><replaceable>role-resync-conflict-policy</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-p<arg choice="req" rep="norepeat"><replaceable>ping_timeout</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-u<arg choice="req" rep="norepeat"><replaceable>val</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-d<arg choice="req" rep="norepeat"><replaceable>hash_alg</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-o</arg>
      <arg choice="opt" rep="norepeat">-n</arg>
      <arg choice="opt" rep="norepeat">-g<arg choice="req" rep="norepeat"><replaceable>congestion_policy</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-f<arg choice="req" rep="norepeat"><replaceable>val</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-h<arg choice="req" rep="norepeat"><replaceable>val</replaceable></arg></arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">syncer</arg>
      <arg choice="opt" rep="norepeat">-a<arg choice="req" rep="norepeat"><replaceable>dev_minor</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-r<arg choice="req" rep="norepeat"><replaceable>rate</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-e<arg choice="req" rep="norepeat"><replaceable>extents</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-v<arg choice="req" rep="norepeat"><replaceable>verify-hash-alg</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-c<arg choice="req" rep="norepeat"><replaceable>cpu-mask</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-C<arg choice="req" rep="norepeat"><replaceable>csums-hash-alg</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-R</arg>
      <arg choice="opt" rep="norepeat">-p<arg choice="req" rep="norepeat"><replaceable>plan_time</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-s<arg choice="req" rep="norepeat"><replaceable>fill_target</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-d<arg choice="req" rep="norepeat"><replaceable>delay_target</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-m<arg choice="req" rep="norepeat"><replaceable>max_rate</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-n<arg choice="req" rep="norepeat"><replaceable>ond-policy</replaceable></arg></arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">disconnect</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">detach</arg>
      <arg choice="opt" rep="norepeat">-f</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">down</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">primary</arg>
      <arg choice="opt" rep="norepeat">-f</arg>
      <arg choice="opt" rep="norepeat">-o</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">secondary</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">verify</arg>
      <arg choice="opt" rep="norepeat">-s<arg choice="req" rep="norepeat"><replaceable>start-position</replaceable></arg></arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">invalidate</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">invalidate-remote</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">wait-connect</arg>
      <arg choice="opt" rep="norepeat">-t<arg choice="req" rep="norepeat"><replaceable>wfc_timeout</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-d<arg choice="req" rep="norepeat"><replaceable>degr_wfc_timeout</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-o<arg choice="req" rep="norepeat"><replaceable>outdated_wfc_timeout</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-w</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">wait-sync</arg>
      <arg choice="opt" rep="norepeat">-t<arg choice="req" rep="norepeat"><replaceable>wfc_timeout</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-d<arg choice="req" rep="norepeat"><replaceable>degr_wfc_timeout</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-o<arg choice="req" rep="norepeat"><replaceable>outdated_wfc_timeout</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-w</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">role</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">cstate</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">dstate</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">status</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">resize</arg>
      <arg choice="opt" rep="norepeat">-d<arg choice="req" rep="norepeat"><replaceable>size</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-f<arg choice="req" rep="norepeat"><replaceable>assume-peer-has-space</replaceable></arg></arg>
      <arg choice="opt" rep="norepeat">-c<arg choice="req" rep="norepeat"><replaceable>assume-clean</replaceable></arg></arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">check-resize</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">pause-sync</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">resume-sync</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">outdate</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">show-gi</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">get-gi</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">show</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">suspend-io</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">resume-io</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">events</arg>
      <arg choice="opt" rep="norepeat">-u</arg>
      <arg choice="opt" rep="norepeat">-a</arg>
    </cmdsynopsis>
    <cmdsynopsis sepchar=" ">
      <command moreinfo="none">drbdsetup</command>
      <arg choice="req" rep="norepeat">
        <replaceable>device</replaceable>
      </arg>
      <arg choice="plain" rep="norepeat">new-current-uuid</arg>
      <arg choice="opt" rep="norepeat">-c</arg>
    </cmdsynopsis>
  </refsynopsisdiv>
  <refsect1>
    <title>Description</title>
    <para>      drbdsetup is used to associate DRBD devices with their backing
      block devices, to set up DRBD device pairs to mirror their
      backing block devices, and to inspect the configuration of
      running DRBD devices.
    </para>
  </refsect1>
  <refsect1>
    <title>Note</title>
    <para>      drbdsetup is a low level tool of the DRBD program suite. It is
      used by the data disk and drbd scripts to communicate with
      the device driver.
    </para>
  </refsect1>
  <refsect1>
    <title>Commands</title>
    <para>      Each drbdsetup sub-command might require arguments and bring its own
      set of options. All values have default units which might be overruled
      by K, M or G. These units are defined in the usual way (e.g. K = 2^10 = 1024).
    </para>
    <refsect2>
      <title>Common options</title>
      <para>        All drbdsetup sub-commands accept these two options

	<variablelist><varlistentry><term><option>--create-device</option></term><listitem><para>		In case the specified DRBD device (minor number) does not
		exist yet, create it implicitly.
	      </para></listitem></varlistentry><varlistentry><term><option>--set-defaults</option></term><listitem><para>		When <option>--set-defaults</option> is given on the
		command line, all options of the invoked sub-command that
		are not explicitly set are reset to their default values.
	      </para></listitem></varlistentry></variablelist>

      </para>
    </refsect2>
    <refsect2>
      <title>disk</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>disk</secondary>
      </indexterm>
      <para>	Associates <replaceable>device</replaceable> with
	<replaceable>lower_device</replaceable> to store its data blocks on.
	The <option>-d</option> (or <option>--disk-size</option>) should
	only be used if you wish not to use as much as possible from the
	backing block devices.
	If you do not use <option>-d</option>, the <replaceable>device</replaceable>
	is only ready for use as soon as it was connected to its peer once.
	(See the <option>net</option> command.)
      </para>
      <variablelist>
        <varlistentry>
          <term><option>-d</option>,
	  <option>--disk-size <replaceable>size</replaceable></option></term>
          <listitem>
            <para>	      You can override DRBD's size determination method with this
	      option. If you need to use the device before it was ever
	      connected to its peer, use this option to pass the
	      <replaceable>size</replaceable> of the DRBD device to the
	      driver. Default unit is sectors (1s = 512 bytes).
	    </para>
            <para>	      If you use the <replaceable>size</replaceable> parameter in drbd.conf,
	      we strongly recommend to add an explicit unit postfix.
	      drbdadm and drbdsetup used to have mismatching default units.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-e</option>,
	  <option>--on-io-error <replaceable>err_handler</replaceable></option></term>
          <listitem>
            <para>	      If the driver of the <replaceable>lower_device</replaceable>
	      reports an error to DRBD, DRBD will mark the disk as inconsistent,
	      call a helper
	      program, or detach the device from its backing storage and
	      perform all further IO by requesting it from the peer. The
	      valid <replaceable>err_handlers</replaceable> are:
	      <option>pass_on</option>, <option>call-local-io-error</option>
	      and <option>detach</option>.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-f</option>,
	  <option>--fencing <replaceable>fencing_policy</replaceable></option></term>
          <listitem>
            <para>	      Under <option>fencing</option> we understand preventive
	      measures to avoid situations where both nodes are primary
	      and disconnected (AKA split brain).
	    </para>
            <para>	      Valid fencing policies are:
	    </para>
            <variablelist>
              <varlistentry>
                <term>
                  <option>dont-care</option>
                </term>
                <listitem>
                  <para>		  This is the default policy. No fencing actions are done.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>resource-only</option>
                </term>
                <listitem>
                  <para>		  If a node becomes a disconnected primary, it tries to outdate
		  the peer's disk. This is done by calling the fence-peer
		  handler. The handler is supposed to reach the other node over
		  alternative communication paths and call 'drbdadm outdate
		  res' there.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>resource-and-stonith</option>
                </term>
                <listitem>
                  <para>		  If a node becomes a disconnected primary, it freezes all
		  its IO operations and calls its fence-peer handler. The
		  fence-peer handler is supposed to reach the peer over
		  alternative communication paths and call 'drbdadm outdate
		  res' there. In case it cannot reach the peer, it should
		  stonith the peer. IO is resumed as soon as the situation
		  is resolved. In case your handler fails, you can resume
		  IO with the <option>resume-io</option> command.
		</para>
                </listitem>
              </varlistentry>
            </variablelist>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-b</option>,
	  <option>--use-bmbv</option></term>
          <listitem>
            <para>	      In case the backing storage's driver has a merge_bvec_fn()
	      function,  DRBD has to
	      pretend that it can only process IO requests in units
	      not larger than 4 KiB. (At time of writing the only known 
	      drivers which
	      have such a function are: md (software raid driver),
	      dm (device mapper - LVM) and DRBD itself)</para>
            <para>	      To get best performance out of DRBD on top of software
	      raid (or any other driver with a merge_bvec_fn() function)
	      you might enable this option, if you know for sure
	      that the merge_bvec_fn() function will deliver the same
	      results on all nodes of your cluster. I.e. the physical
	      disks of the software raid are exactly of the same type.
              USE THIS OPTION ONLY IF YOU KNOW WHAT YOU ARE DOING.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-a</option>, <option>--no-disk-barrier</option></term>
          <term><option>-i</option>, <option>--no-disk-flushes</option></term>
          <term><option>-D</option>, <option>--no-disk-drain</option></term>
          <listitem>
            <para>              DRBD has four implementations to express write-after-write dependencies to
              its backing storage device. DRBD will use the first method that is
              supported by the backing storage device and that is not disabled by the user.
	    </para>
            <para>              When selecting the method you should not only base your decision on the
              measurable performance. In case your backing storage device has a volatile
              write cache (plain disks, RAID of plain disks) you should use one
              of the first two. In case your backing storage device has battery-backed
              write cache you may go with option 3.
	      Option 4 (disable everything, use "none") <emphasis>is dangerous</emphasis>
	      on most IO stacks, may result in write-reordering, and if so,
	      can theoretically be the reason for data corruption, or disturb
	      the DRBD protocol, causing spurious disconnect/reconnect cycles.
	      <emphasis>Do not use</emphasis> <option>no-disk-drain</option>.
            </para>
            <para>              Unfortunately device mapper (LVM) might not support barriers.
            </para>
            <para>              The letter after "wo:" in /proc/drbd indicates with method is currently in
              use for a device: b, f, d, n. The implementations:
            </para>
            <variablelist>
              <varlistentry>
                <term>barrier</term>
                <listitem>
                  <para>                  The first requires that the driver of the
                  backing storage device support barriers (called 'tagged command queuing' in
                  SCSI and 'native command queuing' in SATA speak). The use of this
                  method can be disabled by the <option>--no-disk-barrier</option> option.
	        </para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>flush</term>
                <listitem>
                  <para>                  The second requires that the backing device support disk flushes (called
                  'force unit access' in the drive vendors speak). The use of this method
                  can be disabled using the <option>--no-disk-flushes</option> option.
	        </para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>drain</term>
                <listitem>
                  <para>                  The third method is simply to let write requests drain before
                  write requests of a new reordering domain are issued. That was the
                  only implementation before 8.0.9.
	        </para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>none</term>
                <listitem>
                  <para>                  The fourth method is to not express write-after-write dependencies to
		  the backing store at all, by also specifying <option>--no-disk-drain</option>.
		  This <emphasis>is dangerous</emphasis>
		  on most IO stacks, may result in write-reordering, and if so,
		  can theoretically be the reason for data corruption, or disturb
		  the DRBD protocol, causing spurious disconnect/reconnect cycles.
		  <emphasis>Do not use</emphasis> <option>--no-disk-drain</option>.
		  </para>
                </listitem>
              </varlistentry>
            </variablelist>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-m</option>,
	  <option>--no-md-flushes</option></term>
          <listitem>
            <para>		  Disables the use of disk flushes and barrier BIOs when
		  accessing the meta data device. See the notes
		  on <option>--no-disk-flushes</option>.
		</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-s</option>,
	<option>--max-bio-bvecs</option></term>
          <listitem>
            <para>      In some special circumstances the device mapper stack manages to
      pass BIOs to DRBD that violate the constraints that are set forth
      by DRBD's merge_bvec() function and which have more than one bvec.
      A known example is:
      phys-disk -&gt; DRBD -&gt; LVM -&gt; Xen -&gt; missaligned partition (63) -&gt; DomU FS.
      Then you might see "bio would need to, but cannot, be split:" in
      the Dom0's kernel log. </para>
            <para>      The best workaround is to proper align the partition within
      the VM (E.g. start it at sector 1024). That costs 480 KiB of storage.
      Unfortunately the default of most Linux partitioning tools is
      to start the first partition at an odd number (63). Therefore
      most distributions install helpers for virtual linux machines will
      end up with missaligned partitions.
      The second best workaround is to limit DRBD's max bvecs per BIO
      (i.e., the <option>max-bio-bvecs</option> option) to 1, but that might cost performance.</para>
            <para>      The default value of <option>max-bio-bvecs</option> is 0, which means that
      there is no user imposed limitation.
    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-t</option>,
	  <option>--disk-timeout <replaceable>disk_timeout</replaceable></option></term>
          <listitem>
            <para>	      If the driver of the <replaceable>lower_device</replaceable>
	      does not finish an IO request within <replaceable>disk_timeout</replaceable>,
	      DRBD considers the disk as failed. If DRBD is connected to a remote host,
	      it will reissue local pending IO requests to the peer, and ship all new
	      IO requests to the peer only. The disk state advances to diskless, as soon
	      as the backing block device has finished all IO requests.</para>
	      <para>      The default value of is 0, which means that no timeout is enforced.
	      The default unit is 100ms. This option is available since 8.3.12.
	      </para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
    <refsect2>
      <title>net</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>net</secondary>
      </indexterm>
      <para>	Sets up the <replaceable>device</replaceable> to listen on
	<replaceable>af:local_addr:port</replaceable> for incoming connections
	and to try to connect to <replaceable>af:remote_addr:port</replaceable>.
	If <replaceable>port</replaceable> is omitted, 7788 is used as default.
        If <replaceable>af</replaceable> is omitted <option>ipv4</option> gets
        used. Other supported address families are <option>ipv6</option>,
        <option>ssocks</option> for Dolphin Interconnect Solutions' "super sockets"
        and <option>sdp</option> for Sockets Direct Protocol (Infiniband).
      </para>
      <para>	On the TCP/IP link the specified <replaceable>protocol</replaceable>
	is used. Valid protocol specifiers are A, B, and C.</para>
      <para>Protocol A: write IO is reported as completed, if it has reached
	local disk and local TCP send buffer.</para>
      <para>Protocol B: write IO is reported as completed, if it has reached
	local disk and remote buffer cache.</para>
      <para>Protocol C: write IO is reported as completed, if it has
	reached both local and remote disk.</para>
      <variablelist>
        <varlistentry>
          <term><option>-c</option>,
	    <option>--connect-int <replaceable>time</replaceable></option></term>
          <listitem>
            <para>		In case it is not possible to connect to the remote DRBD
		device immediately, DRBD keeps on trying to connect. With
		this option you can set the time between two retries. The
		default value is 10 seconds, the unit is 1 second.
		</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-i</option>,
	    <option>--ping-int <replaceable>time</replaceable></option></term>
          <listitem>
            <para>	      If the TCP/IP connection linking a DRBD device pair is idle
	      for more than <replaceable>time</replaceable> seconds, DRBD
	      will generate a keep-alive packet to check if its partner is
	      still alive. The default value is 10 seconds, the unit is 1 second.
	      </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-t</option>,
	  <option>--timeout <replaceable>val</replaceable></option></term>
          <listitem>
            <para>	      If the partner node fails to send an expected response packet
	      within <replaceable>val</replaceable>
	      tenths of a second, the partner node
	      is considered dead and therefore the TCP/IP connection is
	      abandoned. The default value is 60 (= 6 seconds).
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-S</option>,
	  <option>--sndbuf-size <replaceable>size</replaceable></option></term>
          <listitem>
            <para>	      The socket send buffer is used to store packets sent to the
	      secondary node, which are not yet acknowledged (from a network
	      point of view) by the secondary node. When using protocol A,
	      it might be necessary to increase the size of this data
	      structure in order to increase asynchronicity between primary
	      and secondary nodes. But keep in mind that more asynchronicity
	      is synonymous with more data loss in the case of a primary
	      node failure. Since 8.0.13 resp. 8.2.7 setting the <replaceable>size</replaceable>
              value to 0 means that the kernel should autotune this.
              The default <replaceable>size</replaceable> is
	      0, i.e. autotune.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-r</option>,
	  <option>--rcvbuf-size <replaceable>size</replaceable></option></term>
          <listitem>
            <para>	      Packets received from the network are stored in the socket receive
              buffer first. From there they are consumed by DRBD. Before 8.3.2 the
              receive buffer's size was always set to the size of the socket
              send buffer. Since 8.3.2 they can be tuned independently.
              A value of 0 means that the kernel should autotune this.
              The default <replaceable>size</replaceable> is
	      0, i.e. autotune.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-k</option>,
	  <option>--ko-count <replaceable>count</replaceable></option></term>
          <listitem>
            <para>	      In case the secondary node fails to complete a single write
	      request for <replaceable>count</replaceable> times the
	      <replaceable>timeout</replaceable>, it is expelled from the
	      cluster, i.e. the primary node goes into StandAlone mode.
	      The default is 0, which disables this feature.
	      </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-e</option>, <option>--max-epoch-size
	  <replaceable>val</replaceable></option></term>
          <listitem>
            <para>	      With this option the maximal number of write requests between
	      two barriers is limited. Should be set to the same as
	      <option>--max-buffers</option>. Values smaller than 10 can
	      lead to degraded performance. The default value is 2048.
	      </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-b</option>,
	  <option>--max-buffers <replaceable>val</replaceable></option></term>
          <listitem>
            <para>	      With this option the maximal number of buffer pages allocated
	      by DRBD's receiver thread is limited. Should be set to the
	      same as <option>--max-epoch-size</option>. Small values
	      could lead to degraded performance. The default value is 2048, the minimum 32.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-u</option>,
	  <option>--unplug-watermark <replaceable>val</replaceable></option></term>
          <listitem>
            <para>	      When the number of pending write requests on the standby
	      (secondary) node exceeds the unplug-watermark, we trigger
	      the request processing of our backing storage device.
	      Some storage controllers deliver better performance with small
	      values, others deliver best performance when the value is set to
	      the same value as max-buffers. Minimum 16, default 128, maximum
	      131072.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-m</option>,
	  <option>--allow-two-primaries </option></term>
          <listitem>
            <para>	      With this option set you may assign primary role to both nodes. You
	      only should use this option if you use a shared storage
	      file system on top of DRBD. At the time of writing the only
	      ones are: OCFS2 and GFS. If you use this option with any
	      other file system, you are going to crash your nodes and to
	      corrupt your data!
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-a</option>,
	  <option>--cram-hmac-alg </option><replaceable>alg</replaceable></term>
          <listitem>
            <para>	      You need to specify the HMAC algorithm to enable peer
	      authentication at all. You are strongly encouraged to use
	      peer authentication.
	      The HMAC algorithm will be used for the challenge
	      response authentication of the peer. You may specify any
	      digest algorithm that is named in /proc/crypto.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-x</option>,
	  <option>--shared-secret </option><replaceable>secret</replaceable></term>
          <listitem>
            <para>	      The shared secret used in peer authentication. May be up to
	      64 characters.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-A</option>,
	  <option>--after-sb-0pri </option><replaceable>asb-0p-policy</replaceable></term>
          <listitem>
            <para>	    possible policies are:
	    </para>
            <variablelist>
              <varlistentry>
                <term>
                  <option>disconnect</option>
                </term>
                <listitem>
                  <para>		  No automatic resynchronization, simply disconnect.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>discard-younger-primary</option>
                </term>
                <listitem>
                  <para>		  Auto sync from the node that was primary before the split-brain situation occurred.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>discard-older-primary</option>
                </term>
                <listitem>
                  <para>		Auto sync from the node that became primary as second during
		the split-brain situation.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>discard-zero-changes</option>
                </term>
                <listitem>
                  <para>		In case one node did not write anything since the split
		brain became evident, sync from the node that wrote something
		to the node that did not write anything. In case none wrote
		anything this policy uses a random decision to perform
		a "resync" of 0 blocks. In case both have written something
		this policy disconnects the nodes.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>discard-least-changes</option>
                </term>
                <listitem>
                  <para>		Auto sync from the node that touched more blocks during the
		split brain situation.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>discard-node-NODENAME</option>
                </term>
                <listitem>
                  <para>		Auto sync to the named node.
		</para>
                </listitem>
              </varlistentry>
            </variablelist>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-B</option>,
	  <option>--after-sb-1pri </option><replaceable>asb-1p-policy</replaceable></term>
          <listitem>
            <para>	    possible policies are:
	    </para>
            <variablelist>
              <varlistentry>
                <term>
                  <option>disconnect</option>
                </term>
                <listitem>
                  <para>		  No automatic resynchronization, simply disconnect.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>consensus</option>
                </term>
                <listitem>
                  <para>		  Discard the version of the secondary if the outcome
                  of the <option>after-sb-0pri</option> algorithm would also
		  destroy the current secondary's data. Otherwise disconnect.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>discard-secondary</option>
                </term>
                <listitem>
                  <para>		  Discard the secondary's version.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>call-pri-lost-after-sb</option>
                </term>
                <listitem>
                  <para>		  Always honor the outcome of the <option>after-sb-0pri
		  </option> algorithm. In case it decides the current
		  secondary has the correct data, call the
		  <option>pri-lost-after-sb</option> on the current primary.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>violently-as0p</option>
                </term>
                <listitem>
                  <para>		  Always honor the outcome of the <option>after-sb-0pri
		  </option> algorithm. In case it decides the current
		  secondary has the correct data, accept a possible instantaneous
		  change of the primary's data.
		</para>
                </listitem>
              </varlistentry>
            </variablelist>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-C</option>,
	  <option>--after-sb-2pri </option><replaceable>asb-2p-policy</replaceable></term>
          <listitem>
            <para>	    possible policies are:
	    </para>
            <variablelist>
              <varlistentry>
                <term>
                  <option>disconnect</option>
                </term>
                <listitem>
                  <para>		  No automatic resynchronization, simply disconnect.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>call-pri-lost-after-sb</option>
                </term>
                <listitem>
                  <para>		  Always honor the outcome of the <option>after-sb-0pri
		  </option> algorithm. In case it decides the current
		  secondary has the right data, call the
		  <option>pri-lost-after-sb</option> on the current primary.
		</para>
                </listitem>
              </varlistentry>
              <varlistentry>
                <term>
                  <option>violently-as0p</option>
                </term>
                <listitem>
                  <para>		  Always honor the outcome of the <option>after-sb-0pri
		  </option> algorithm. In case it decides the current
		  secondary has the right data, accept a possible instantaneous
		  change of the primary's data.
		</para>
                </listitem>
              </varlistentry>
            </variablelist>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-P</option>,
	  <option>--always-asbp</option></term>
          <listitem>
            <para>	      Normally the automatic after-split-brain policies are only 
	      used if current states of the UUIDs do not indicate the 
	      presence of a third node.
	    </para>
            <para>	      With this option you request that the automatic 
	      after-split-brain policies are used as long as the data
	      sets of the nodes are somehow related. This might cause
	      a full sync, if the UUIDs indicate the presence of a third
	      node. (Or double faults have led to strange UUID sets.)
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-R</option>,
	  <option>--rr-conflict </option><replaceable>role-resync-conflict-policy</replaceable></term>
          <listitem>
            <para>	      This option sets DRBD's behavior when DRBD deduces from its
	      meta data that a resynchronization is needed, and the SyncTarget
	      node is already primary. The possible settings are:
	      <option>disconnect</option>,
	      <option>call-pri-lost</option> and
	      <option>violently</option>. While <option>disconnect</option>
	      speaks for itself, with the <option>call-pri-lost</option>
	      setting the <option>pri-lost</option> handler is called
	      which is expected to either change the role of the node to
	      secondary, or remove the node from the cluster.
	      The default is <option>disconnect</option>.</para>
            <para>	      With the <option>violently</option> setting you allow DRBD
	      to force a primary node into SyncTarget state. This means
	      that the data exposed by DRBD changes to
	      the SyncSource's version of the data instantaneously.
	      USE THIS OPTION ONLY IF YOU KNOW WHAT YOU ARE DOING.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-d</option>,
	  <option>--data-integrity-alg </option><replaceable>hash_alg</replaceable></term>
          <listitem>
            <para>	      DRBD can ensure the data integrity of the user's data on the network
	      by comparing hash values. Normally this is ensured by the 16 bit checksums
	      in the headers of TCP/IP packets. This option
	      can be set to any of the kernel's data digest algorithms.
              In a typical kernel configuration you should have
              at least one of <option>md5</option>, <option>sha1</option>, and <option>crc32c</option>
              available. By default this is not enabled.
	    </para>
            <para>See also the notes on data integrity on the drbd.conf manpage.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-o</option>,
	  <option>--no-tcp-cork </option></term>
          <listitem>
            <para>	      DRBD usually uses the TCP socket option TCP_CORK to hint to the network
              stack when it can expect more data, and when it should flush out what it
              has in its send queue. There is at least one network
              stack that performs worse when one uses this hinting method. Therefore
              we introduced this option, which disable the setting and clearing of
              the TCP_CORK socket option by DRBD.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-p</option>,
	  <option>--ping-timeout </option><replaceable>ping_timeout</replaceable></term>
          <listitem>
            <para>	      The time the peer has to answer to a keep-alive packet. In case the peer's reply is not received within this
                time period, it is considered dead. The default unit is tenths of a second,
                the default value is 5 (for half a second).
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-D</option>,
	  <option>--discard-my-data </option></term>
          <listitem>
            <para>	      Use this option to manually recover from a split-brain
	      situation. In case you do not have any automatic after-split-brain policies selected, the nodes refuse to
	      connect. By passing this option you make this node a
	      sync target immediately after successful connect.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-n</option>,
	  <option>--dry-run </option></term>
          <listitem>
            <para>	      Causes DRBD to abort the connection process after the resync
	      handshake, i.e. no resync gets performed. You can find out which resync
	      DRBD would perform by looking at the kernel's log file.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-g</option>, <option>--on-congestion </option><replaceable>congestion_policy</replaceable></term>
          <term><option>-f</option>, <option>--congestion-fill </option><replaceable>fill_threshold</replaceable></term>
          <term><option>-h</option>, <option>--congestion-extents </option><replaceable>active_extents_threshold</replaceable></term>
          <listitem>
            <para>By default DRBD blocks when the available TCP send queue becomes full.
	      That means it will slow down the application that generates the write
	      requests that cause DRBD to send more data down that TCP connection.
	    </para>
	    <para>When DRBD is deployed with DRBD-proxy it might be more desirable that
	      DRBD goes into AHEAD/BEHIND mode shortly before the send queue becomes full.
	      In AHEAD/BEHIND mode DRBD does no longer replicate data, but still keeps
	      the connection open.</para>
	    <para>The advantage of the AHEAD/BEHIND mode is that the
	      application is not slowed down, even if DRBD-proxy's buffer is
	      not sufficient to buffer all write requests. The downside is that
	      the peer node falls behind, and that a resync will be necessary to
	      bring it back into sync. During that resync the peer node will have
	      an inconsistent disk. </para>
	    <para>Available <replaceable>congestion_policy</replaceable>s are <option>block</option>
	      and <option>pull-ahead</option>. The default is <option>block</option>.
	      <replaceable>Fill_threshold</replaceable> might be in the range of 0 to 10GiBytes. The
	      default is 0 which disables the check. <replaceable>Active_extents_threshold</replaceable>
	      has the same limits as <option>al-extents</option>.</para>
	    <para>The AHEAD/BEHIND mode and its settings are available since DRBD 8.3.10.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
    <refsect2>
      <title>syncer</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>syncer</secondary>
      </indexterm>
      <para>	Changes the synchronization daemon parameters of
	<replaceable>device</replaceable> at runtime.
      </para>
      <variablelist>
        <varlistentry>
          <term><option>-r</option>,
	  <option>--rate <replaceable>rate</replaceable></option></term>
          <listitem>
            <para>	      To ensure smooth operation of the application on top of DRBD,
	      it is possible to limit the bandwidth that  may be used by
	      background synchronization. The default is 250 KiB/sec, the
	      default unit is KiB/sec.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-a</option>,
	  <option>--after <replaceable>minor</replaceable></option></term>
          <listitem>
            <para>	      Start resync on this device only if the device with
	      <replaceable>minor</replaceable> is already in connected
	      state. Otherwise this device waits in SyncPause state.
	  </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-e</option>,
	  <option>--al-extents <replaceable>extents</replaceable></option></term>
          <listitem>
            <para>	      DRBD automatically performs hot area detection. With this
	      parameter you control how big the hot area (=active set) can
	      get. Each extent marks 4M of the backing storage. In case a
	      primary node leaves the cluster unexpectedly, the areas covered
	      by the active set must be resynced upon rejoining of the failed
	      node. The data structure is stored in the meta-data area,
	      therefore each change of the active set is a write operation
	      to the meta-data device. A higher number of extents gives
	      longer resync times but less updates to the meta-data. The
	      default number of <replaceable>extents</replaceable> is
	      127. (Minimum: 7, Maximum: 3843)
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-v</option>,
	  <option>--verify-alg <replaceable>hash-alg</replaceable></option></term>
          <listitem>
            <para>              During online verification (as initiated by the 
              <command moreinfo="none">verify</command> sub-command),
              rather than doing a bit-wise comparison, DRBD applies a hash function 
              to the contents of every block being verified, and compares that
              hash with the peer. This option defines the hash algorithm being
              used for that purpose. It can be set to any of the kernel's data 
              digest algorithms. In a typical kernel configuration you should have
              at least one of <option>md5</option>, <option>sha1</option>, and <option>crc32c</option>
              available. By default this is not enabled; you must set this
              option explicitly in order to be able to use on-line device verification.
	    </para>
            <para>See also the notes on data integrity on the drbd.conf manpage.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-c</option>,
	  <option>--cpu-mask <replaceable>cpu-mask</replaceable></option></term>
          <listitem>
            <para>	      Sets the cpu-affinity-mask for DRBD's kernel threads of this
	      device. The default value of <replaceable>cpu-mask</replaceable> is
	      0, which means that DRBD's kernel threads should be spread over
	      all CPUs of the machine. This value must be given in hexadecimal
              notation. If it is too big it will be truncated.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-C</option>,
	  <option>--csums-alg <replaceable>hash-alg</replaceable></option></term>
          <listitem>
            <para>             A resync process sends all marked data blocks form the source to
             the destination node, as long as no <option>csums-alg</option> is
             given. When one is specified the resync process exchanges hash values of all
             marked blocks first, and sends only those data blocks over, that have different
             hash values.</para>
            <para>This setting is useful for DRBD setups with low bandwidth links.
             During the restart of a crashed primary node, all blocks covered by the
             activity log are marked for resync. But a large part of those will actually
             be still in sync, therefore using <option>csums-alg</option> will lower
             the required bandwidth in exchange for CPU cycles.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-R</option>,
	  <option>--use-rle</option></term>
          <listitem>
            <para>              During resync-handshake, the dirty-bitmaps of the nodes are
              exchanged and merged (using bit-or), so the nodes will have the
              same understanding of which blocks are dirty. On large devices,
              the fine grained dirty-bitmap can become large as well, and the
              bitmap exchange can take quite some time on low-bandwidth links.
	    </para>
            <para>              Because the bitmap typically contains compact areas where all
              bits are unset (clean) or set (dirty), a simple run-length
              encoding scheme can considerably reduce the network traffic
              necessary for the bitmap exchange.
	    </para>
            <para>              For backward compatibilty reasons, and because on fast links this
              possibly does not improve transfer time but consumes cpu cycles,
              this defaults to off.
	    </para>
            <para>              Introduced in 8.3.2.
	    </para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><option>-p</option>,
	  <option>--c-plan-ahead <replaceable>plan_time</replaceable></option></term>
          <term><option>-s</option>,
	  <option>--c-fill-target <replaceable>fill_target</replaceable></option></term>
          <term><option>-d</option>,
	  <option>--c-delay-target <replaceable>delay_target</replaceable></option></term>
          <term><option>-M</option>,
	  <option>--c-max-rate <replaceable>max_rate</replaceable></option></term>
          <listitem>
            <para>The dynamic resync speed controller gets enabled with setting
	      <replaceable>plan_time</replaceable> to a positive value. It aims to
	      fill the buffers along the data path with either a constant amount of data
	      <replaceable>fill_target</replaceable>, or aims to have a constant
	      delay time of <replaceable>delay_target</replaceable> along the
	      path. The controller has an upper bound of <replaceable>max_rate</replaceable>.
	    </para>
	    <para>
	      By <replaceable>plan_time</replaceable> the agility of the controller is configured.
	      Higher values yield for slower/lower responses of the controller to deviation
	      from the target value. It should be at least 5 times RTT.
	      For regular data paths a <replaceable>fill_target</replaceable>
	      in the area of 4k to 100k is appropriate. For a setup that contains drbd-proxy
	      it is advisable to use <replaceable>delay_target</replaceable> instead.
	      Only when <replaceable>fill_target</replaceable> is set to 0 the controller
	      will use <replaceable>delay_target</replaceable>. 5 times RTT is a reasonable
	      starting value. <replaceable>Max_rate</replaceable> should be set to the
	      bandwidth available between the DRBD-hosts and the machines hosting
	      DRBD-proxy, or to the available disk-bandwidth.
	    </para>
	    <para>
	      The default value of <replaceable>plan_time</replaceable> is 0, the default unit is
	      0.1 seconds. <replaceable>Fill_target</replaceable> has 0 and sectors as default unit.
	      <replaceable>Delay_target</replaceable> has 1 (100ms) and 0.1 as default unit.
	      <replaceable>Max_rate</replaceable> has 10240 (100MiB/s) and KiB/s as default unit.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-m</option>,
	  <option>--c-min-rate <replaceable>min_rate</replaceable></option></term>
          <listitem>
	    <para>We track the disk IO rate caused by the resync, so we can
	      detect non-resync IO on the lower level device. If the lower
	      level device seems to be busy, and the current resync rate is
	      above <replaceable>min_rate</replaceable>, we throttle the resync.
	    </para>
	    <para>
	      The default value of <replaceable>min_rate</replaceable> is 4M,
	      the default unit is k.  If you want to not throttle at all, set
	      it to zero, if you want to throttle always, set it to one.
	    </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><option>-n</option>,
	  <option>--on-no-data-accessible <replaceable>ond-policy</replaceable></option></term>
          <listitem>
            <para>This setting controls what happens to IO requests on a degraded, disk less node
	      (I.e. no data store is reachable). The available policies are <option>io-error</option>
	      and <option>suspend-io</option>.</para>
	    <para>
	      If <replaceable>ond-policy</replaceable> is set to <option>suspend-io</option> you
	      can either resume IO by attaching/connecting the last lost data storage, or by
	      the <command moreinfo="none">drbdadm resume-io <replaceable>res</replaceable></command>
	      command. The latter will result in IO errors of course.
	    </para>
	    <para>
	      The default is <option>io-error</option>. This setting is available since DRBD 8.3.9.
	    </para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
    <refsect2>
      <title>primary</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>primary</secondary>
      </indexterm>
      <para>	Sets the <replaceable>device</replaceable> into primary role. This
	means that applications (e.g. a file system) may open the
	<replaceable>device</replaceable> for read and write access. Data
	written to the <replaceable>device</replaceable> in primary role are
	mirrored to the device in secondary role.
      </para>
      <para>	Normally it is not possible to set both devices of a connected DRBD device
	pair to primary role. By using the <option>--allow-two-primaries</option>
	option, you override this behavior and instruct DRBD to allow two
	primaries.
      </para>
      <variablelist>
        <varlistentry>
          <term><option>-o</option>,
	  <option>--overwrite-data-of-peer</option></term>
          <listitem>
            <para>Alias for --force.
	    </para>
          </listitem>
        </varlistentry>
      </variablelist>
      <variablelist>
        <varlistentry>
          <term><option>-f</option>,
	  <option>--force</option></term>
          <listitem>
            <para>	      Becoming primary fails if the local replica is
	      not up-to-date. I.e. when it is inconsistent, outdated of consistent.
	      By using this option you can force it into
	      primary role anyway. USE THIS OPTION ONLY IF YOU KNOW WHAT
	      YOU ARE DOING.
	    </para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
    <refsect2>
      <title>secondary</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>secondary</secondary>
      </indexterm>
      <para>	Brings the <replaceable>device</replaceable> into secondary role.
	This operation fails as long as at least one application (or file
	system) has opened the device.
      </para>
      <para>	It is possible that both devices of a connected DRBD device pair are secondary.
      </para>
    </refsect2>
    <refsect2>
      <title>verify</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>verify</secondary>
      </indexterm>
      <para>        This initiates on-line device verification. During on-line verification,
        the contents of every block on the local node are compared to those on
        the peer node. Device verification progress can be monitored via
        <filename moreinfo="none">/proc/drbd</filename>.
        Any blocks whose content differs from that of the corresponding block
        on the peer node will be marked out-of-sync in DRBD's on-disk bitmap; they
        are <emphasis>not</emphasis> brought back in sync automatically. To
        do that, simply disconnect and reconnect the resource.
      </para>
      <para>        If on-line verification is already in progress, this command
        silently does nothing.
      </para>
      <para>	This command will fail if the <replaceable>device</replaceable> is
	not part of a connected device pair.
      </para>
      <para>See also the notes on data integrity on the drbd.conf manpage.</para>
      <variablelist>
        <varlistentry>
          <term><option>-s</option>,
	  <option>--start <replaceable>start-sector</replaceable></option></term>
          <listitem>
            <para>              Since version 8.3.2, on-line verification should resume from the
	      last position after connection loss.  It may also be started from
	      an arbitrary position by setting this option.
            </para>
            <para>              Default unit is sectors. You may also specify a unit explicitly.
              The <option>start-sector</option> will be rounded down to a multiple of 8 sectors (4kB).
            </para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
    <refsect2>
      <title>invalidate</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>invalidate</secondary>
      </indexterm>
      <para>	This forces the local device of a pair of connected DRBD devices
	into SyncTarget state, which means that all data blocks of the
	device are copied over from the peer.
      </para>
      <para>	This command will fail if the <replaceable>device</replaceable> is
	not part of a connected device pair.
      </para>
    </refsect2>
    <refsect2>
      <title>invalidate-remote</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>invalidate-remote</secondary>
      </indexterm>
      <para>	This forces the local device of a pair of connected DRBD devices
	into SyncSource state, which means that all data blocks of the
	device are copied to the peer.
      </para>
      <para>
	On a disconnected device, this will set all bits in the out of sync bitmap.
	As a side affect this suspend updates to the on disk activity log. Updates
	to the on disk activity log will get resumes automatically when necessary.
      </para>
    </refsect2>
    <refsect2>
      <title>wait-connect</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>wait-connect</secondary>
      </indexterm>
      <para>	Returns as soon as the <replaceable>device</replaceable> can
	communicate with its partner device.
      </para>
      <variablelist>
        <varlistentry>
          <term><option>-t</option>,
	  <option>--wfc-timeout <replaceable>wfc_timeout</replaceable></option></term>
          <term><option>-d</option>,
	  <option>--degr-wfc-timeout <replaceable>degr_wfc_timeout</replaceable></option></term>
          <term><option>-o</option>,
	  <option>--outdated-wfc-timeout <replaceable>outdated_wfc_timeout</replaceable></option></term>
          <term><option>-w</option>, <option>--wait-after-sb</option></term>
          <listitem>
            <para>	      This command will fail if the
	      <replaceable>device</replaceable> cannot communicate with its
	      partner for <replaceable>timeout</replaceable>
	      seconds. If the peer was working before this node was
	      rebooted, the <replaceable>wfc_timeout</replaceable> is used. If the peer was already
	      down before this node was rebooted, the <replaceable>degr_wfc_timeout</replaceable>
	      is used. If the peer was sucessfully outdated before this
              node was rebooted the <replaceable>outdated_wfc_timeout</replaceable> is used.
	      The default value for all those timeout values
	      is 0 which means to wait forever.
	      In case the connection status goes down to StandAlone because
              the peer appeared but the devices had a split brain situation,
              the default for the command is to terminate. You can change this
              behavior with the <option>--wait-after-sb</option> option.
	    </para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>
    <refsect2>
      <title>wait-sync</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>wait-sync</secondary>
      </indexterm>
      <para>	Returns as soon as the <replaceable>device</replaceable> leaves any
	synchronization into connected state. The options
	are the same as with the <replaceable>wait-connect</replaceable>
	command.
      </para>
    </refsect2>
    <refsect2>
      <title>disconnect</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>disconnect</secondary>
      </indexterm>
      <para>	Removes the information set by the <option>net</option> command
	from the <replaceable>device</replaceable>. This means
	that the <replaceable>device</replaceable> goes into unconnected
	state and will no longer listen for incoming connections.
      </para>
    </refsect2>
    <refsect2>
      <title>detach</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>detach</secondary>
      </indexterm>
      <para>	Removes the information set by the <option>disk</option> command
	from the <replaceable>device</replaceable>. This means
	that the <replaceable>device</replaceable> is detached from its
	backing storage device.
      <variablelist>
        <varlistentry>
          <term><option>-f</option>,
	  <option>--force</option></term>
          <listitem>
            <para>A regular detach returns after the disk state finally reached
	    diskless. As a consequence detaching from a frozen backing block device
	    never terminates.</para>
	    <para>On the other hand A forced detach returns immediately. It allows
	    you to detach DRBD from a frozen backing block device. Please note that
	    the disk will be marked as failed until all pending IO requests where
	    finished by the backing block device.
	    </para>
          </listitem>
        </varlistentry>
      </variablelist>
      </para>
    </refsect2>
    <refsect2>
      <title>down</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>down</secondary>
      </indexterm>
      <para>	Removes all configuration information from the
	<replaceable>device</replaceable> and forces it back to
	unconfigured state.
      </para>
    </refsect2>
    <refsect2>
      <title>role</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>role</secondary>
      </indexterm>
      <para>	Shows the current roles of the <replaceable>device</replaceable> and
          its peer, as <replaceable>local</replaceable>/<replaceable>peer</replaceable>.
      </para>
    </refsect2>
    <refsect2>
      <title>state</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>state</secondary>
      </indexterm>
      <para>Deprecated alias for "role"</para>
    </refsect2>
    <refsect2>
      <title>cstate</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>cstate</secondary>
      </indexterm>
      <para>	Shows the current connection state of the
	<replaceable>device</replaceable>.
      </para>
    </refsect2>
    <refsect2>
      <title>dstate</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>dstate</secondary>
      </indexterm>
      <para>	Shows the current states of the backing storage devices, as <replaceable>local</replaceable>/<replaceable>peer</replaceable>.
      </para>
    </refsect2>
    <refsect2>
      <title>status</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>status</secondary>
      </indexterm>
      <para>	Shows the current status of the device in XML-like format. Example output:
	<programlisting format="linespecific">&lt;resource minor="0" name="s0" cs="SyncTarget" st1="Secondary" st2="Secondary"
         ds1="Inconsistent" ds2="UpToDate" resynced_precent="5.9" /&gt;</programlisting>
      </para>
    </refsect2>
    <refsect2>
      <title>resize</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>resize</secondary>
      </indexterm>
      <para>This causes DRBD to reexamine the size of the
	<replaceable>device</replaceable>'s backing storage device.  To
	actually do online growing you need to extend the backing storages
	on both devices and call the <option>resize</option> command on one of
        your nodes.
      </para>
      <para>The <option>--assume-peer-has-space</option> allows you to
	resize a device which is currently not connected to the peer.
	Use with care, since if you do not resize the peer's disk as well,
	further connect attempts of the two will fail.
      </para>
      <para>When the <option>--assume-clean</option> option is given
	DRBD will skip the resync of the new storage. Only do this if you
	know that the new storage was initialized to the same content
	by other means.
      </para>
    </refsect2>
    <refsect2>
      <title>check-resize</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>check-resize</secondary>
      </indexterm>
      <para>To enable DRBD to detect offline resizing of backing devices
	this command may be used to record the current size of backing
	devices. The size is stored in files in /var/lib/drbd/ named
	drbd-minor-??.lkbd
      </para>
      <para>
	This command is called by
	<command moreinfo="none">drbdadm resize <replaceable>res</replaceable></command> after
	<command moreinfo="none">drbdsetup <replaceable>device</replaceable> resize</command> returned.
      </para>
    </refsect2>
    <refsect2>
      <title>pause-sync</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>pause-sync</secondary>
      </indexterm>
      <para>        Temporarily suspend an ongoing resynchronization by setting the local
	pause flag. Resync only progresses if neither the local nor the
	remote pause flag is set. It might be desirable to postpone DRBD's
	resynchronization after eventual resynchronization of the backing
	storage's RAID setup.
      </para>
    </refsect2>
    <refsect2>
      <title>resume-sync</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>resume-sync</secondary>
      </indexterm>
      <para>        Unset the local sync pause flag.
      </para>
    </refsect2>
    <refsect2>
      <title>outdate</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>outdate</secondary>
      </indexterm>
      <para>        Mark the data on the local backing storage as outdated. An outdated
	device refuses to become primary. This is used in conjunction with
	<option>fencing</option> and by the peer's <option>fence-peer</option> handler.
      </para>
    </refsect2>
    <refsect2>
      <title>show-gi</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>show-gi</secondary>
      </indexterm>
      <para>        Displays the device's data generation identifiers verbosely.
      </para>
    </refsect2>
    <refsect2>
      <title>get-gi</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>get-gi</secondary>
      </indexterm>
      <para>        Displays the device's data generation identifiers.
      </para>
    </refsect2>
    <refsect2>
      <title>show</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>show</secondary>
      </indexterm>
      <para>	Shows all available configuration information of the
	<replaceable>device</replaceable>.
      </para>
    </refsect2>
    <refsect2>
      <title>suspend-io</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>suspend-io</secondary>
      </indexterm>
      <para>	This command is of no apparent use and just provided for the sake
	of completeness.
      </para>
    </refsect2>
    <refsect2>
      <title>resume-io</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>resume-io</secondary>
      </indexterm>
      <para>	If the fence-peer handler fails to stonith the peer node,
	and your <option>fencing</option> policy is set to
	resource-and-stonith, you can unfreeze IO operations with this
	command.
      </para>
    </refsect2>
    <refsect2>
      <title>events</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>events</secondary>
      </indexterm>
      <para>      	Displays every state change of DRBD and all calls to helper
	programs. This might be used to get notified of DRBD's state
	changes by piping the output to another program.

	<variablelist><varlistentry><term><option>-a</option>,
	    <option>--all-devices</option></term><listitem><para>		Display the events of all DRBD minors.
	      </para></listitem></varlistentry><varlistentry><term><option>-u</option>,
	    <option>--unfiltered</option></term><listitem><para>		This is a debugging aid that displays the content of
		all received netlink messages.
	      </para></listitem></varlistentry></variablelist>
      </para>
    </refsect2>
    <refsect2>
      <title>new-current-uuid</title>
      <indexterm significance="normal">
        <primary>drbdsetup</primary>
        <secondary>new-current-uuid</secondary>
      </indexterm>
      <para>        Generates a new current UUID and rotates all other UUID values. This
        has at least two use cases, namely to skip the initial sync, and to
        reduce network bandwidth when starting in a single node configuration
        and then later (re-)integrating a remote site.
      </para>
      <para>        Available option:

	<variablelist><varlistentry><term><option>-c</option>,
	    <option>--clear-bitmap</option></term><listitem><para>		Clears the sync bitmap in addition to generating a new current UUID.
	      </para></listitem></varlistentry></variablelist>
      </para>
      <para>        This can be used to skip the initial sync, if you want to start from scratch.
        This use-case does only work on "Just Created" meta data.
        Necessary steps:
        <orderedlist numeration="arabic" inheritnum="ignore" continuation="restarts"><listitem><simpara>            On <emphasis>both</emphasis> nodes, initialize meta data and configure the device.
          </simpara><simpara><command moreinfo="none">drbdadm -- --force create-md <replaceable>res</replaceable></command></simpara></listitem><listitem><simpara>            They need to do the initial handshake, so they know their sizes.
          </simpara><simpara><command moreinfo="none">drbdadm up <replaceable>res</replaceable></command></simpara></listitem><listitem><simpara>            They are now Connected Secondary/Secondary Inconsistent/Inconsistent.
            Generate a new current-uuid and clear the dirty bitmap.
          </simpara><simpara><command moreinfo="none">drbdadm -- --clear-bitmap new-current-uuid <replaceable>res</replaceable></command></simpara></listitem><listitem><simpara>            They are now Connected Secondary/Secondary UpToDate/UpToDate.
            Make one side primary and create a file system.
          </simpara><simpara><command moreinfo="none">drbdadm primary <replaceable>res</replaceable></command></simpara><simpara><command moreinfo="none">mkfs -t <replaceable>fs-type</replaceable> $(drbdadm sh-dev <replaceable>res</replaceable>)</command></simpara></listitem></orderedlist>
      </para>
      <para>	One obvious side-effect is that the replica is full of old garbage
	(unless you made them identical using other means), so any
	online-verify is expected to find any number of out-of-sync blocks.
      </para>
      <para><emphasis>You must not use this on pre-existing data!</emphasis>
        Even though it may appear to work at first glance, once you switch to
        the other node, your data is toast, as it never got replicated.
        So <emphasis>do not leave out the mkfs</emphasis> (or equivalent).
      </para>
      <para>        This can also be used to shorten the initial resync of a cluster where the second node
        is added after the first node is gone into production, by means of disk shipping.
	This use-case works on disconnected devices only, the device may be in
        primary or secondary role.
      </para>
      <para>The necessary steps on the current active server are:
        <orderedlist numeration="arabic" inheritnum="ignore" continuation="restarts"><listitem><simpara><command moreinfo="none">drbdsetup <replaceable>device</replaceable> new-current-uuid --clear-bitmap</command></simpara></listitem><listitem><simpara>	    Take the copy of the current active server. E.g. by pulling a disk out of
	    the RAID1 controller, or by copying with dd. You need to copy the actual
	    data, and the meta data.
            </simpara></listitem><listitem><simpara><command moreinfo="none">drbdsetup <replaceable>device</replaceable> new-current-uuid</command></simpara></listitem></orderedlist>
        Now add the disk to the new secondary node, and join it to the cluster. You will
        get a resync of that parts that were changed since the first call to
        <command moreinfo="none">drbdsetup</command> in step 1.
      </para>
    </refsect2>
  </refsect1>
  <refsect1>
    <title>Examples</title>
    <para>      For examples, please have a look at the
      <ulink url="http://www.drbd.org/users-guide/"><citetitle>DRBD User's Guide</citetitle></ulink>.
      </para>
  </refsect1>
  <refsect1>
    <title>Version</title>
    <simpara>This document was revised for version 8.3.2 of the DRBD distribution.
    </simpara>
  </refsect1>
  <refsect1>
    <title>Author</title>
    <simpara>Written by Philipp Reisner <email>philipp.reisner@linbit.com</email>
            and Lars Ellenberg <email>lars.ellenberg@linbit.com</email>
    </simpara>
  </refsect1>
  <refsect1>
    <title>Reporting Bugs</title>
    <simpara>Report bugs to <email>drbd-user@lists.linbit.com</email>.
    </simpara>
  </refsect1>
  <refsect1>
    <title>Copyright</title>
    <simpara>Copyright 2001-2008 LINBIT Information Technologies,
Philipp Reisner, Lars Ellenberg. This  is  free software;
see the source for copying conditions.  There is NO warranty;
not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
    </simpara>
  </refsect1>
  <refsect1>
    <title>See Also</title>
    <para><citerefentry><refentrytitle>drbd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>drbd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>drbddisk</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>drbdadm</refentrytitle><manvolnum>8</manvolnum></citerefentry>, <ulink url="http://www.drbd.org/users-guide/"><citetitle>DRBD User's Guide</citetitle></ulink>,
      <ulink url="http://www.drbd.org/"><citetitle>DRBD web site</citetitle></ulink></para>
  </refsect1>
</refentry>