[Dovecot] Basic clustered filesystem advice

[Stan Hoeppner]

On 9/16/2013 8:24 AM, Simon Fraser wrote:
> 
> Time marches on, and I need to continue the service migration. I'd still
> like to use Dovecot (we're migrating away from Cyrus).  I'm assuming the
> only other alternative without existing shared storage is to use DRBD
> and a cluster file system to provide the replication, and to ensure
> Director is enabled.  Are there any things to watch for surrounding
> this? 

Just the basics:

1.  DRBD is limited to two nodes
2.  Twice as many disks are required vs single host, NFS share, SAN LUN
3.  GFS2/OCFS2 metadata exchange is slow and gets slower with load
4.  maildir doesn't scale well due to metadata modification rate

DRBD may or may not be your best solution.

I didn't read the previous incarnation of this thread as the subject
lacked keywords in my area of interest/expertise.  This subject one has
both cluster and filesystem.  If you'd like to further discuss storage
options for your Dovecot workload I'd be glad to.  Knowing your
current/future mailbox count, avg mail and mailbox size, msgs/day, etc,
is required for proper analysis.

-- 
Stan