16 Jul
2012
16 Jul
'12
6:10 p.m.
The only issue I see right now is Dovecot index file write bashing if a user accesses their mailbox from multiple locations at the same time, and I gave that example in the previous post. That seems to be more and more common these days but still not the norm for 80%+ of the mailboxes we have.
We have a similar setup and solved the problem for us this way:
- The delivering mail servers (postfix+dovecot) don't write any index files, so we can use round robin here.
- We have an additional layer of proxy servers between the loadbalancers and the dovecot IMAP servers, that try to make sessions sticky. For this we use the IMAP/POP3 proxy code of nginx with a PHP script that does some database voodoo, normalizes the user name and based on all this decides which IMAP backend server to use. This is based on the username (not the IP), so it is sticky for multiple IMAP and POP3 connections from different IPs. I think dovecot director should be able to do similar things (our setup is a little bit older and needs some more flexibility).
Tschoeeee
Roland-- Roland Rosenfeld - Content Delivery - NED - Technik NetCologne Gesellschaft für Telekommunikation mbH - HRB 25580, AG Köln Am Coloneum 9 50829 Köln Tel.: +49 221 2222-373 Fax: +49 221 2222-7373 Geschäftsführer: Dr. Hans Konle (Sprecher), Karl-Heinz Zankel