[CentOS] RAID on Email Server

Rainer Duffner rainer at ultra-secure.de
Fri Oct 10 21:42:15 UTC 2008

Matt schrieb:
> 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 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.
> Matt
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How many concurrent users?
If you stay with SATA, you will probably have to increase the amount of
disks in you storage-array (depending on the number of users).
A SATA disk does only 80 I/Os per second or so - and clamav+spamassassin
alone will consume a lot of these.
Try to put their working-directories on a swap-backed tmpfs.


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