I spent about 6 months fighting with Apple XSAN and Apple OSX mail to
try to create a redundant cyrus mail cluster. First of all, don't try
it, it is a waste of time. Apple states that mail on an XSAN is not
supported. The reason is that it simply won't run. The Xsan can't
handle the large amount of small files and will do things like
disconnect or corrupting the file system.
So my suggestion is to make sure that your san can handle the large
amount of files that a mail server will be reading and dumping. The
Xsan had severe problems to the point of file system corruption while
trying to deal with them, so make sure your san can handle it.
Our final solution which we are still in the process of finishing is to
create a linux cluster with two servers each with their own XRAID
backend. Using replication, we mirror one server to the other. Using
some sophisticated software we wrote, we can validate the mailstore ages
and then create a fully see-sawable cluster system.
Good luck!
David
Chris St. Pierre wrote:
Chad--
We've put /var/lib/imap and /var/spool/imap on a SAN and have two
machines -- one active, and one hot backup. If the active server
fails, the other mounts the storage and takes over. This is not yet
in production, but it's a pretty simple setup and can be done without
running any bleeding edge software, and it appears that it will work
fine. There's no need to use a SAN, either -- you could share your
mail storage out via NFS with the same effect.
We're going production with this in mid-August; if you'd like to know
how everything goes, drop me a note in a month or so.
Chris St. Pierre
Unix Systems Administrator
Nebraska Wesleyan University
On Thu, 27 Jul 2006, Chad A. Prey wrote:
OK...I'm searching for strategies to have a "realtime" email backup in
the event of backend failure. We've been running cyrus-imap for about a
year and a half with incredible success. Our failures have all been due
to using junky storage.
One idea is to have a continuous rsync of the cyrus /var/spool/imap
and /var/lib/imap to another server
I've also considered delivering email to two discreet email backends and
keeping the /var/lib/imap file sync'd . I don't think I can use murder
to do this.
Is anyone out there using RHEL in a cluster that would like to share
their architecture? Any contractors out there that want to get paid to
help us implement?
Chad P.
cprey@xxxxxxxx
Salk Institute for Biological Studies
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