Last time i checked the free version of DRBD only supports 2 nodes.
The paid version supports 16 nodes. This however, doesnt mean that
you cannot use the storage via NFS or SMB/CIFS mount point. Only that
the DRBD replication will only happen to 2 nodes. If a third node is
supported on the free version, it would be for quorum only.
They might have changed it since, but i doubt it.
On Aug 24, 2009, at 10:51 AM, Eric Jon Rostetter wrote:
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
--
Eric Rostetter
The Department of Physics
The University of Texas at Austin
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