Quoting Guy <wyldf...@gmail.com>:
I'm looking at the possibility of running a pair of servers with Dovecot LDA/imap/pop3 using internal drives with DRBD and GFS (or other clustered FS) for the mail storage and ext3 for the root drive.
I'm in testing right now with this setup. Two Dell PE 2900 servers (quad core @ 2.3 GHz, 8 GB RAM, raid 10 for the GFS+DRBD disk, raid 1 for the ext3 disks). Running DRBD as a master/master setup. I added a third node for webmail (Dell PE 2650), but it doesn't do the DRBD or GFS. It is there mostly to make a 3-node cluster versus 2-node cluster, to avoid split-brain type situations. And of course to do the webmail. :) Using MailScanner as the MTA, dovecot for pop/imap, mailman for mailing lists, Horde/IMP/etc for webmail. All held together with RHCS on CentOS 5.3. All services run on only one node at a time, with failover... This may or may not help with GFS lock contention (not for /var/spool/mail, since it is always accessed from both nodes at once, but yes for dovecot indexes since they are only ever accessed on one node at a time, etc). This is probably where performance will really be decided (GFS lock contention). Cluster Status for mailer @ Mon Aug 24 10:27:12 2009 Member Status: Quorate Member Name ID Status ------ ---- ---- ------ mailer1-hb.localdomain 1 Online, rgmanager mailer2-hb.localdomain 2 Online, Local, rgmanager webmail1-hb.localdomain 3 Online, rgmanager Service Name Owner (Last) State ------- ---- ----- ------ ----- service:Apache mailer1-hb.localdomain started service:Dovecot mailer1-hb.localdomain started service:MailMan mailer2-hb.localdomain started service:MailScanner mailer2-hb.localdomain started service:VIP-MAIL mailer1-hb.localdomain started service:VIP-SMTP mailer2-hb.localdomain started service:WebMail webmail1-hb.localdomain started
Has anyone had experience with a setup like the one I'm suggesting? What was performance like with Dovecot using GFS?
So far it is early testing. 63 users, but only about 12 of those are "power users". The performance has been real good so far, but as I say, not many users yet. My GFS is sharing the mail log files (via syslog-ng, what would otherwise be /var/log/maillog), the dovecot index files, the /var/spool/mail/ mbox spool (yes, I use mbox), and "shared" configuration files for the two nodes (mailman data, MailScanner/Sendmail configs, dovecot config, clamav/spamd config, procmail config, apache config, ssl certificates, etc). If interested, I can let you know about performance once I know more...
Thanks Guy
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