Using a SAN/GPFS with cyrus

[Ken Murchison]

Prentice Bisbal wrote:

> I'm installing Cyrus on a ssytem that will have access to an IBM FAStT 
> SAN with GPFS (a parallel filesystem allowing multiple servers to share 
> a filesystem on a SAN).
> 
> For redundancy, I was thinking of creating the IMAP folder dir and spool 
> dir on the SAN and then having two mailservers setup identically using 
> cyrus. If the primary server  goes down for any reason, the secondary 
> would automatically begin receiving/delivering mail based on the MX 
> records in DNS.
> 
> Would this present any problems with cyrus if two servers are accessing 
> the same directories/files? GPFS should manage file sharing, but I'm 
> wondering if there are any know problems with Cyrus in this configuration.
> 
> Has anyone done this before?

Sharing mailboxes.db is prone to problems, if one machine trashes it, 
then the other machine(s) need to be halted while the db is 
reconstructed.  I'm involved in something similar using 3 or 4 load 
balanced Sun machines on a QFS SAN.  The current setup keeps separate 
mailboxes.db, deliver.db and tls_sessions.db on each machine (which 
means that duplicate delivery and Sieve aren't foolproof across 
machines).  I have modified imapd and mupdate to keep mailboxes.db in 
sync across the machines.  This code is currently being beta-tested, and 
I haven't heard any complaints for weeks.

If you are interested in looking at this, checkout the unified-imapd 
branch from CVS.

-- 
Kenneth Murchison     Oceana Matrix Ltd.
Software Engineer     21 Princeton Place
716-662-8973 x26      Orchard Park, NY 14127
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