From: Adrian Ulrich (pfixblinkenlights.ch)
Date: Mon Oct 02 2006 - 11:38:58 CDT

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Hi,

> Have used iostat and I see lots of small transactions.

It's a Mailserver afterall ;-)

 
> What do you mean by "svctm/%util"?

Service-Time + Percent-Busy

I don't have access to a FreeBSD-Host ATM, but the output of solaris
iostat -xnz 5 looks like this: (Output on FreeBSD should be similar):

    r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
   20.6 8.9 1281.1 53.1 1.8 0.3 62.1 11.2 9 21 c0d0

If %b(usy) is above ~>70% you are having speed-issues with your
storage system.

> Ideally I would like to decrease incoming mails only to these two machines.
> Other machines are fine.

Limit the number of smtpd processes (= Incoming mail) on this two hosts
   

> I am still trying to
> convince the powers that be.. to get a SCSI setup for these domains.

How about a 'shared storage' for all 4 Backends?

<ADV>
 I'm a very happy NetApp(.com) customer: We are using a bunch
 of FAS270 Boxes for Mailqueues and never had any (Storage-Related)
 speed issues. They can do NFS, FCP, iSCSI (urgs) provide Raid4 and
 Raid4-DP (Think 'raid6' -> Double Parity) you can create
 Snapshots (without any performance issues unlike
 ${everyone_else's_solution}) .. etc..
</ADV>

> > You are using Maildir, correct?
> Correct. Maildir run off Courier IMAP, serving imap and pop3.

So switching to Dovecot might help: IMAP with dovecot seems to be
pretty fast.

Regards,
 Adrian

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