Need advice on building a Cyrus IMAP cluster

[Dave McMurtrie]

Dave McMurtrie wrote:

> Though I have no experience with it, I seem to recall that someone 
> attempted to use GFS with an active/active Cyrus cluster and it was a 
> disaster.  It was mentioned either on info-cyrus or in the Cyrus wiki. 
> If google doesn't help you find this, I can try to remember where I read it.
> 

Replying to myself:

Close...  It was GPFS, not GFS.  Here's the info-cyrus post I was 
thinking of:

http://lists.andrew.cmu.edu/pipermail/info-cyrus/2004-February/008975.html

A couple points that Mr. Ulmer makes are valid.  When we first went into 
production with the active/active cluster at Pitt, it ground to a halt 
under heavy load because of mmap() usage.  We ended up changing the 
map_refresh() code so it would MAP_PRIVATE instead of MAP_SHARED.  This 
relieved the cluster of the burden of tracking the mmap() state across 
all of the nodes.

Also, we did not use Berkeley DB or Skiplist for anything.  All of our 
databases were flat.  I think BDB may use shared memory, which 
definitely won't work across cluster nodes using only a distributed 
filesystem.  If this is the case, BDB just can't be used.

HTH,

Dave
-- 
Dave McMurtrie, SPE
Email Systems Team Leader
Carnegie Mellon University,
Computing Services