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#!/usr/bin/perl -wT
# Check various system parameters for PostgreSQL. This needs to be run as root.
#
# (C) 2005 Martin Pitt <mpitt@debian.org>
use strict;
use lib '/usr/share/postgresql-common';
use PgCommon;
# Check write cache setting for given drive.
# Arguments: <device>
# Returns: 0 = disabled, 1 = enabled, -1: could not determine
sub get_device_write_cache {
open DRV, $_[0] or return -1;
sub HDIO_GET_WCACHE () {0x30e;}
my $pval = pack 'l', 0;
ioctl DRV, &HDIO_GET_WCACHE, $pval or return -1;
my ($val) = unpack 'l', $pval;
close DRV;
return $val;
}
error 'This command needs to be executed as root' if $> != 0;
# collect write cache-enabled drives with databases
my %drive_wcache;
my %seen;
for my $v (get_versions) {
for my $c (get_version_clusters $v) {
my $datadir = PgCommon::cluster_data_directory $v, $c;
my $drv = PgCommon::get_file_device $datadir;
$drv =~ s/[0-9]+$//;
unless (exists $seen{$drv}) {
$drive_wcache{$drv} = 1 if (get_device_write_cache $drv) > 0;
$seen{$drv} = 1;
}
}
}
my @unsave_drives = keys %drive_wcache;
if (@unsave_drives) {
print 'Warning: The following devices contain databases and have write
caching enabled: ', (join ' ', @unsave_drives), '
This could destroy the integrity of your databases in the event of power
failure. Consider disabling the write cache with "hdparm -W 0 <device>".
';
}
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