On Thu, Jun 02, 2011 at 10:37:23AM +0200, Cor Bosman wrote:
> We use a setup as seen on http://grab.by/agCb for about 30.000 
> simultaneous(!) imap connections. 

This might as well be a diagram of my network, although, if I remember,
you're running quite a few more netapps clusters than I am. ;)

> We have 2 Foundry loadbalancers. They check the health of the directors. We 
> have 3 directors, and each one runs Brandon's poolmon script 
> (https://github.com/brandond/poolmon). This script removes real servers out 
> of the director pool. The dovecot imap servers are monitored with nagios just 
> to tell us when they're down. 

I'm using a hacked up version of poolmon.  The only important changes
are that it actually logs into the real server rather than just making a
connection to it and that has heuristics to prevent the real servers
from flapping and added a timeout to scan_host so if a real server
blocks after the connection is established it won't hang indefinitely.

> This setup has been absolutely rock solid for us. I have not touched the 
> whole system since november and we have not seen any more corruption of meta 
> data, which is the whole reason for the directors.  Kudos to Timo for fixing 
> this difficult problem.

That is always good to hear!

I'd be a lot happier if I was able to monitor the directors and make
sure that they were connected and correctly synced with eachother - even
as a protection from human error rather than anticipated software failure.

-- 
Kelsey Cummings - [email protected]      sonic.net, inc.
System Architect                          2260 Apollo Way
707.522.1000                              Santa Rosa, CA 95407

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