Using a SAN/GPFS with cyrus

[Prentice Bisbal]

Ken, I'm not too familiar with QFS SANs. Does that have a filesystem 
interfacewhere the filesystem itself allows multiple SAN clients to 
access the same filesystem, etc?

What if the 2nd system was treated as a hot spare, and would't actually 
do any mailserving functions until the primary server is shutdown. (ie 
the switchover wouldn't be automatic - it would require human intervention).

Prentice


Ken Murchison wrote:
> 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.
>