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What's the best possible email failover solution



Odhiambo Washington <wash_(_at_)_wananchi_(_dot_)_com> wrote:

> * Bill Moran <wmoran_(_at_)_potentialtech_(_dot_)_com> [20040622 00:57]: wrote:
> > Matthew Seaman <m_(_dot_)_seaman_(_at_)_infracaninophile_(_dot_)_co_(_dot_)_uk> wrote:
> > 
> > > On Mon, Jun 21, 2004 at 05:25:20PM -0400, Bill Moran wrote:
> > >  
> > > > The return can be significant.  The company I am doing this for provides IMAP
> > > > mail services for business.  If a filesystem crashes and service is down for a
> > > > while, we can easily lose clients.  If we had some sort of failover, we'd be
> > > > able to just switch the IP on the backup machine and life would be good.
> > > > 
> > > > "long way to go" is what I'm trying to establish.  I was hoping to find
> > > > something workable without reinventing the wheel.  For example, Postgresql can
> > > > do real-time replication between two Postgresql servers using Slony.  If I can
> > > > find an IMAP server that will keep the mail folders in PostgreSQL, I've got my
> > > > failover system ... tada!
> > > 
> > >     http://wiki.dovecot.org/moin.cgi/DovecotPostgresql
> > 
> > Unfortunately, this only keeps the user database in Postgresql, but not the
> > mailboxes themselves.  We already have the equivalent of this using LDAP, and
> > I'm in the process of setting up a slave LDAP server for redundancy.
> > 
> > It's the mailboxes themselves that are difficult to get.  Best we've got right
> > now is backing up the Cyrus mail folders using rsync ... but this is very time-
> > consuming, and (thus) only done once a day.  In order for it to be done right,
> > Cyrus has to be shut down while it's backing up.
> 
> Hello Bill and everyone,
> 
> I know it is already August. I did not read this list all this
> time, leave alone the thread!
> But anyway, Bill says they use LDAP, yes? How about this solution:
> 
> # High Availability Mail server                          
> http://bsdvault.net/sections.php?op=viewarticle&artid=99 
> http://bsdvault.net/sections.php?op=viewarticle&artid=100
> 
> Looks like what Bill wanted, no?

Thanks for the input.

Unfortunately, this only handles the delivery side of things.  If users are
using IMAP to manage their mail on the server, the two machines will get
out of sync, unless there's some way to tell the IMAP server to manage the
mail on both machines simultaenously.

-- 
Bill Moran
Potential Technologies
http://www.potentialtech.com