Question about lmtp.lock

[Ben Carter]

info-cyrus -- Amos Gouaux wrote:

> David G Mcmurtrie wrote:
>
>> On Mon, 13 Dec 2004, Michael Loftis wrote:
>>
>>
>>> There are a number of different lockfiles that cyrus uses during it's
>>> lifecycle.  Though one thing you need to know is that it is not 
>>> designed to
>>> run like you're attempting to run it.  Each cyrus instance is meant 
>>> to be
>>> standalone, and running them all from a shared disk could very 
>>> likely cause
>>> mailbox corruption, as well as skiplist corruption for the seen/subs
>>> entries and such.  The only part of cyrus that may be multi-node 
>>> from same
>>> storage safe is the BerkeleyDB stuff used for the mailboxes and 
>>> deliver DBs.
>>
>>
>>
>> The cluster filesystem honors POSIX locking semantics across all 
>> nodes in
>> the cluster.
>>
>>
>>> Take a look at MURDER, that's what you'll want if you want to cluster
>>> Cyrus.  MURDER+heartbeat with a shared storage medium provides for 
>>> failover
>>> (heartbeat is a separate, generic failover package).
>>
>>
>>
>> We chose a clustered environment over murder because we wanted 
>> scalability
>> and redundancy, not just scalability.
>
>
> You're using the Cyrus code from CVS (3.0 branch?), right? Based on 
> what I've picked up in the past, you'll need that for such a clustered 
> environment. I know Ken had done some work on such a layout, but I 
> don't know what the present state is. (I think in that situation there 
> were some issues with Sun's QFS, but not sure.)
>
> Amos
>
We're expecting very few issues here - if any.  As long as the locking 
works across the cluster (and it is supposed to of course), the only 
issue we expect is to have to add a VxFS-specific ioctl call to the 
Cyrus code to extend the flat mailboxes file in large chunks - maybe 
just one extension operation.  That's because in Veritas' CFS, a single 
node masters a given filesystem for metadata updates.

Also, I can't recommend QFS.  In my benchmarks it was a lot slower than 
Veritas' CFS.

Ben

-- 

Ben Carter
University of Pittsburgh/CSSD
bhc at pitt.edu
412-624-6470

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