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.. _imap-features-archiving:
=========
Archiving
=========
Description
===========
When we talk about "Archiving" in Cyrus (from 3.0 onwards) we're not
talking about data retention, what we're really talking about is
time-tiered storage. Elsewhere in these documents we discuss
:ref:`storage tiering <imap-deployment-storage-performance>` based on
things like space limitations or :ref:`scalability
<imap-deployment-storage-scalability>`. Archiving is somewhat like
this, but with an accompanying configuration syntax which determines
the management of the tiered data on an ongoing basis.
Purpose
=======
The general intent of archiving, as deployed within Cyrus, is to allow
administrators to dictate that there be two tiers of data storage for
each mail spool partition: "current" and "archive." The common use case
is to use higher speed storage media for the former, and lower cost
media for the latter; Current goes on SSDs, and Archive goes on
traditional spinning media.
Enabling
========
Archive operation in Cyrus is enabled via the ``archive_enabled``
setting in :cyrusman:`imapd.conf(5)`:
.. include:: /imap/reference/manpages/configs/imapd.conf.rst
:start-after: startblob archive_enabled
:end-before: endblob archive_enabled
Defining
========
The configuration suite provides directives to define these partitions:
.. include:: /imap/reference/manpages/configs/imapd.conf.rst
:start-after: startblob archivepartition-name
:end-before: endblob archivepartition-name
Controlling
===========
And to control the criteria used to manage migration of data between
partitions:
.. include:: /imap/reference/manpages/configs/imapd.conf.rst
:start-after: startblob archive_after
:end-before: endblob archive_after
.. include:: /imap/reference/manpages/configs/imapd.conf.rst
:start-after: startblob archive_maxsize
:end-before: endblob archive_maxsize
.. include:: /imap/reference/manpages/configs/imapd.conf.rst
:start-after: startblob archive_keepflagged
:end-before: endblob archive_keepflagged
.. note::
Further explanation is probably required for the
``archive_maxsize`` option. The value is a threshold. Messages
larger than this threshold will be immediately put onto the archive
partition, rather than waiting ``archive_days`` number of days.
This is to keep the high speed storage available for the largest
number of "current" messages.
So ``archive_maxsize`` is not the maximum size of messages which
will be archived, but rather is the threshold above which they will
immediately be.
Performing
==========
Finally, the actual migration is handled by invoking
:cyrusman:`cyr_expire(8)` with its ``-A`` flag, as shown here in
a sample snippet from :cyrusman:`cyrus.conf(5)` (but could also be done
via ``cron``)::
EVENTS {
...
archive cmd="cyr_expire -A 7d" at=0403
...
}
|
