LARGE single-system Cyrus installs?

[Michael D. Sofka]

On Thursday 04 October 2007 07:32:52 pm Rob Mueller wrote:
> 4. Lots of other little things
>
> a) putting the proc dir on tmpfs is a good idea
> b) make sure you have the right filesystem (on linux, reiserfs is much
> better than ext3 even with ext3s dir hashing) and journaling modes

On a Murder front-end server, could the tls_sessions.db be put on a
tmpfs?  What about mailboxes.db, since the murder master would have
the master copy anyway.  (This would slowdown startup in the case
of the system loosing power.  But, ``the front end servers can be 
considered 'dataless' '' according to: http://cyrusimap.web.cmu.edu/ag.html)

We have a Murder Aggregate with two front-end and three back-end
servers, and the master.   I've noticed the front-end servers are a little
IO bound.  They each have a single disk, and I discovered that half
of the IO wait went away when I buffered the cyrus.log file in syslogd.
But, they still show an average of 5-6% IO Wait for processes.

Moving imap/proc to tmpfs, however, had a negligible effect.

 I'll spec a two-disk system when new front-end's are ordered,
but that would only split system from cyrus.   Would it make more
sense (and, more importantly, would it work and not foobar us) to order
a machine with more memory, and put configdirectory: on tmpfs?  (With
the possible exception of the db snapshots and mboxlist backups.)

Mike

-- 
Michael D. Sofka               sofkam at rpi.edu
C&MT Sr. Systems Programmer,   Email, TeX, Epistemology
Rensselaer Polytechnic Institute, Troy, NY.  http://www.rpi.edu/~sofkam/