[CentOS] RAID on Email Server
John R Pierce
pierce at hogranch.com
Fri Oct 10 17:52:08 UTC 2008
> I have an email server running Exim, Dovecot, Spamassassin, Clam, etc.
> on Centos 4.x 32bit. On occasion I have disk I/O problems. Its
> handling several domains and alot of email. Its currently on a single
> SATA drive. I am thinking of moving too 3 drives with RAID 1 for
> redundancy. RAID 1 will help me on reads but do nothing on writes as
> I understand. I am thinking the majority of my I/O is read though
> not? I imagine quotta checks and all that being done and everytime a
> user checks there email every message in the inbox must be read.
> I guess I am asking if RAID 1 will help my I/O problem much?
> [root at server ~]# w
> 12:04:02 up 2:01, 1 user, load average: 7.02, 7.47, 11.84
> USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
> root pts/0 188.8.131.52.ppp 11:25 0.00s 0.02s 0.00s w
> [root at server ~]# vmstat
> procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
> r b swpd free buff cache si so bi bo in cs us sy id wa
> 0 2 0 1558496 456916 1087224 0 0 198 749 795 537 18 4 27 50
> The above is when its running pretty good.
can you paste the output of `iostat -x 5 5` while its busy ? this will
show definateively how busy your disks are...
the first sample from vmstat, iostat, etc only shows the AVERAGE since
the system booted. the 2nd and beyond samples are the average over the
time intervals specified (5 5 means 5 seconds, 5 samples)
oh, if you don't have iostat, its part of package sysstat, so `yum
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