High availability ... again

[Ken Murchison]

John C. Amodeo wrote:

> I would be very interested to know if anyone is using a Cyrus cluster
> connected to a SAN using a cluster file system.  Would Cyrus die if two
> servers were trying to access the same mailstore / db files?

As long as the filesystem provides correct locking and memory mapping, 
the Cyrus processes don't care.

I'm working with the folks at a local university on such a config.  They 
are using the 2.3 code which has a "replicated" Murder configuration 
that I wrote specifically for this purpose.  This means that the mail 
spool and user meta-data are on the shared filesystem, and that 
mailboxes.db is replicated via the MUPDATE protocol to each server.  The 
only limitation with this is that you really can't share deliver.db or 
tls_sessions.db with any reliability.  The solution to this problem 
would be to use a BDB RPC cyrusdb backend (which I have tested a little) 
or an SQL cyrusdb backend (as yet unwritten).

This config effectively gives you redundancy and load balancing.

> 
> Norman Zhang wrote:
> 
>>>> On a similar note, RedHat have apparently bought Sistina, and GPLed 
>>>> GFS.  This is great news for HA under Linux, IMHO.  I will be 
>>>> testing it soon.
>>>
>>>
>>>
>>> Well, on their site is it listed as "open source", but it is not on 
>>> sources.redhat.com (where LVM2 and device-mapper landed when they 
>>> bought Sistina). In addition, it appears to only be available as part 
>>> of RHEL, which is quite expensive.
>>
>>
>>
>> I think you can get it here, http://sources.redhat.com/cluster/gfs/
>>
>> Norman
>> ---
>> 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
> 
> 
> 


-- 
Kenneth Murchison     Oceana Matrix Ltd.
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