LARGE single-system Cyrus installs?

Eric Luyten Eric.Luyten at
Fri Nov 9 06:05:14 EST 2007

> It seems silly to spend all the money for a T2000 with redundancies
> and SAN and etc.  And then have it choke up when it hits (for us) about
> 10K users.  It seems everyone we talk to scratches their head why this
> system with all it's cores would choke.  We have found even older Sun
> V210 are handling 4K users with negligible load.
> Our working hypothesis is that CYRUS is what is choking up at a certain
> activity level due to bottlenecks with simultaneous access to some shared
> resource for each instance.

Vincent (and others),

I have been following this thread with quite some interest since the start.

We operate a single-instance Cyrus server (2.2.13) on an 8-processor Sun
V1280 with 32 GB of RAM and Solaris 9.
1.3 TB mail data, +50k users, +23M messages in the spool, 200k deliveries
per day (the latter figure being considerably lower than yours, IIRC).

Our server is happily humming away with a load average around 2 (two).

Most of the time we stay under 1,000 IMAP+POP processes combined.
About fifteen percent of our user base is exclusively using POP clients.

Installing an IMAP proxy on our Webmail frontend did cut the number of
active IMAP processes by two-thirds. Webmail sessions are kept "alive"
for a couple of minutes, thereby eliminating many IMAP server process
execs and terminations/wrapups.

Another thought : if your original problem is related to a locking issue
of shared resources, visible upon imapd process termination, the rate of
writing new messages to the spool does not need to be a directly contri-
buting factor.
Were you experiencing the load problem while (briefly) halting deliveries
to the mail spool ?


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