[OT] Re: What's the best possible email failover solution

[Bob Johnson]

Bill Moran wrote:
> "David E. Meier" <dev at eth0.ch> wrote:
> 
>>>Like I said, we'll never know till someone tries it.  It looks like
>>>Dovecot is going to try it eventually, but it seems like they have
>>>other priorities at this time.
>>
>>"Someone" already stores mails in a database: Oracle (Email Server and
>>Collaboration Suite). I set up the Oracle Email Server 5.2 for a company I
>>worked for earlier. And to express it nicely: It was a nightmare! Mails
>>got stuck and rejected because the system was not capable of writing them
>>into the database. Besides, the support for that system was also =0. We
>>were probably the only ones daring to run the system ;-) I am glad I am
>>running cyrus now. Extremly stable and fast.
>>
>>That system was not well thought through at all. I don't know how much
>>work needs to be done for a database email store, but Oracle wasn't
>>(isn't) able to do so.
>

MS Exchange Server also stores email in a database.  This has some great 
benefits, but also some horrible side effects.  If your database gets 
corrupted, you are in deep doodoo, and back in the days when I 
administered an Exchange Server, that happened all too often.  As 
someone mentioned, Cyrus takes a middle approach: it doesn't store the 
email in a database, but maintains a database that tracks the email to 
improve speed.  It seems to scale well.

> 
> It's a shame it wasn't an OSS project, so we could determine if keeping
> mail in a database is a bad idea, or if Oracle just did it poorly.
> 
> The other option is to take what appears to be the best IMAP server out
> there (Cyrus) and figure out a way to do real-time mirroring of the
> mailboxes.  I was wondering if it could be done with Coda, but I don't
> know anything about Coda, and it doesn't look like I'll have time to
> experiment in the near future.
> 

I played with Coda a few years ago, and it seems to have a lot of 
potential.  I keep promising myself I will look at it again.  I recently 
thought of using it for precisely this scenario, but I had only one 
server with two drives, and Coda didn't seem to be the way to go in that 
case.  In fact, I just use rsync nightly, and figure I can live with the 
loss of one day's mail if something dies.

There are other distributed filesystems out there in the Linux world, 
but (IIRC) not many for FreeBSD.  I think it is worth looking at Coda 
for this purpose, although it may have some downside (e.g. not real-time 
enough) that makes it inappropriate.

- Bob