Cyrus HA Scalable Solution? Rsync

[Kevin Baker]

A number of servers with network storage would be ideal.

Unfortunately the initial rollout will require the use of
cheap managed hosting boxes. So we'll be restricted to
local drives.

I guess the hope is to develop a sort of *standard* way to
handle a highly scalable solution with failover with these
inexpensive racks.

The only real missing piece is the replication to a
failover server.

There seem to be a number of solutions at:
http://linas.org/linux

The question is of course what will work best.


Kevin






>
> On Tue, 25 May 2004, Michael Loftis wrote:
>
>>
>>
>> --On Tuesday, May 25, 2004 14:39 -0700 Kevin Baker
>> <kbaker at missionvi.com>
>> wrote:
>>
>>
>> > Thought? This is obviously just a sketch... but I
>> haven't
>> > seen a this done before as far as the failover
>> solution
>> > with rsync and thought it might work pretty well.
>>
>> rsync sucks for large numbers of files/directories.  It
>> has to build an
>> in-memory tree before it even starts syncing.
>>
>> what would be 'nice' to see is something built inside of
>> cyrus to handle
>> multiple backends but that's a pretty complicated bit of
>> beast.  (no i'm
>> not volunteering ;) )
>
> There has been some discussion lately about software
> solutions to provide
> redundancy, but what about buying redundant hardware?
> This may be cheaper
> and more reliable in the long run anyways.
>
> It is not hard to find fully redandunt disk arrays
> (usually in the context
> of SANs, but a full SAN environment is not required).  A
> few examples I've
> come across: Sun T3 Enterprise Pairs, Dell/EMC
> Cx300/500/700.
>
> That pushes the point of failure out to the server (or
> backend server in a
> Murder configuration).  If a server fails for some reason,
> you could have
> a backup server available (also in the SAN, or manually
> connected at the
> time of failure) that mounts the Cyrus partition and
> carries on.
>
> An additional benefit is that these higher end disk arrays
> also typically
> have much better performance.
>
> With all of that said, I'm currently running 35,000
> mailboxes on a single
> Dell 2650 with an external SCSI disk array configured as
> RAID 0+1
> (stripe/mirror).  Mail relaying is handled by separate
> servers, so all
> this box does is IMAP and LMTP delivery.
>
> We use Sun's T3 Enterprise Pairs for user home directories
> and have been
> very happy with the performance and reliability (in
> conjunction with
> Veritas Volume Manager and Veritas File System).  However,
> the Dell/EMC
> solutions are much cheaper and appear to offer the same
> levels of
> reliability.
>
> 	Andy
>
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>

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