Cyrus IMAP Replication Slow Performance

[Brady, Mike]

On 2014-03-16 08:25, Brady, Mike wrote:
> I am looking at using Cyrus IMAP replication as part of setting up a
> DR server at another site but am seeing poor performance during the
> initial sync.
> 
> The servers are on different sites connected by a microwave link.  I
> can rsync between the two servers at slightly better than 30Mb/s, but
> am only getting 1.8Mb/s for the Cyrus IMAP sync.
> 
> I have set Cyrus up as per
> http://cyrusimap.org/docs/cyrus-imapd/2.4.17/install-replication.php
> and the sync does seem to be working.  It is just slow.
> 
> Both systems are up to date Centos 6.5/kolab 3.1 systems.
> 
> Anyone got an ideas on what I can look at to determine why this is so 
> slow?
> 
> Regards
> 
> Mike
> 
The short answer to what was a very long story on this one is hardware 
failure on the replica server.

The slightly longer answer is that the replica server is an HP DL380 
with a P410i with a 256MB cache.  The cache had failed with no alerts 
from the monitoring tools.  HP diagnostic tools just showed no cache 
installed, not a failed module!  HP replaced the cache module.  Once the 
battery recharged the cache reenabled automatically and the transfer 
speed went from 1.8Mb/s to 25Mb/s.  Still not as fast as an rsync, but 
more than adequate for our needs.

Regards

Mike