Cyrus, clusters, GFS - HA yet again

[Dave McMurtrie]

Janne Peltonen wrote:

>And if further splitting of users on more servers is needed - downtime
>again. Moreover, it's confusing for the users to have to determine their
>correct imap server name - we haven't really had trouble with this, but
>it would be nice if the users saw a unified system image.
>
>  
>
If you decide not to pursue a cluster solution, Perdition would probably 
help you with this part.

>Enter weirdness. The first Cyrus to be started starts with no
>complaints and ends up with the correct number (as specified in
>/etc/cyrus.conf) of imapd, imapd -s, pop3d, lmtp etc. processes, all in
>state S, only one process at a time having a write lock on
>/var/lib/imap/socket/xxx-N.lock. 
>
These lockfiles are used to serialize their corresponding processes 
(imap, lmtp, etc) on a per-host basis, not across cluster nodes.  As 
such, you should write these to the local filesystem and not the cluster 
filesystem.  You can accomplish this with symbolic links.

I believe you'll also need to make some minor code changes.  When 
University of Pittsburgh implemented their Cyrus cluster, they added a 
nodename config option and then used that nodename as a filename 
component along with the pid for the lmtp temporary deliver files such 
that the filenames would be unique across cluster nodes.  Without 
modification, only the pid is used as a means to make the filenames unique.

Thanks,

Dave