High availability email server...

[kbaker]

David Korpiewski wrote:
> 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.
One note on this. The SAN configuration sounds great and is a very common 
backup/failover solution, however do not try the NFS. It is well documented that 
Cyrus does not play nice with NFS.



>>
>> 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 at salk.edu
>>> Salk Institute for Biological Studies
>>>
>>>
>>> -- 
>>>
>>> ----
>>> Cyrus Home Page: http://asg.web.cmu.edu/cyrus
>>> Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
>>> List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
>>>
>> ----
>> Cyrus Home Page: http://asg.web.cmu.edu/cyrus
>> Cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu
>> List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
> 


-- 
Kevin Baker
Mission Vi Inc.
kbaker at missionvi.com
858.454.5532
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