imap scalability

[Earl R Shannon]

Hello,

I would in addition recommend that you run your MTA
on a seperate machine(s). If you do use some form of
spam/virus filtering keeping it off the IMAP/POP servers
would probably leave you in a better position, both in
terms of performance and management. Use LMTP to deliver
mail to the IMAP servers. Again, you get some overhead
reduction from running lmtpd instead of postfix and if
you do go with a murder the mail delivery to the correct
mailbox is taken care of.

Regards,
Earl Shannon

Michael Loftis wrote:
> 
> --On Thursday, October 07, 2004 09:54 +0600 denz-wavenet 
> <denz at wavenet.lk> wrote:
> 
>> hi!
>>
>> Requirements:    host 10,0000 IMAP mailboxes
>>
>> Usual setup:  LDAP/SMTP-postfix/cyrus-iamp
> 
> 
> First -- do not run Cyrus over NFS, just don't do it.  Second, do not 
> share spool areas, cyrus does not handle this.
> 
> If you've got compliant clients and servers then NFS *might* work.  You 
> can't use a Linux NFS server, it doesn't qualify.  And I'm pretty sure 
> the Linux NFS client is also in the doesn't' qualify area.  And 
> performance will suck unless you go full Gig-E on a separate back-end 
> network, and even then, DAS or SAN will give you far more attractive 
> results.
> 
> Cyrus broaches the scaling issue with MURDER and using multiple 
> back-ends but they DO NOT SHARE storage.  At all.
> 
> That server may or may not be enough.  It really depends on what you 
> mean by 10,000 users.  IF you mean 10k concurrent connections, no.  Also 
> if it has IDE drives, even if you mean 10k mailboxes forget about it, 
> IDE drives aren't going to keep up, you'll need about 3k random block 
> io/second performance bare minimum using reiserfs and about 30-40G of 
> mail data, other filesystems will have other patterns, ext2/3 will 
> prolly see a LOT more read traffic due to the nature of it's inode 
> layout.  Those numbers come from my live system where we've got around 
> 12k mailboxes and prolly 3k-4k users, and about a million envelopes/day 
> of mail volume coming in, with a LOT being dropped before that count by 
> using DNS blacklists up front.
> 
> Scaling it also depends on your inbound mail, and mail flow, you going 
> to be running AV scanning?  how about SpamAssassin?  going to allow the 
> users to run scripts on their mail (i recommend not....) -- and by that 
> I mean *not* SIEVE, like procmail or similar.
> 
> At first glance, presumign that box has a beefy, and i mean beefy  -- 
> like 7x10K RPM U160 SCSI drives on a real RAID subsystem, like a nice 
> higher end ICP Vortex card -- it should manage, it may get a little 
> tight at times but it should manage it alright.  as long as you dont' 
> mean 10k concurrent sessions, then you're outside the league of a single 
> box, talking about a decent sized load balanced front-end/back-end group 
> of systems.
> ---
> Cyrus Home Page: http://asg.web.cmu.edu/cyrus
> Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
> List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html


-- 
Systems Programmer ,Information Technology Division
NC State University.
http://www.earl.ncsu.edu

Anonymous child "Some people can tell the time by looking at the sun,
		 but I have trouble seeing the numbers."
---
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