Cyrus HA Scalable Solution? Rsync

[Andrew Morgan]

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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