Hi,
if you have only one pair of servers, I think replication via dovecot's
dsync (or doveadm via ssh) where each server holds all emails as a
local storage would be easiest.
There is a caveat with shared folders though. And dovecot replicates
only emails. The index is not included, which means for example that
you'd need 2 databases for quota - otherwise emails would count twice.
Well and any manual index management needs to be done on both sides.
https://wiki.dovecot.org/Replication
Running a cluster filesystem or NFS as a common base is possible but
needs some adjustments of dovecot like turning off caching or memory
mapping, which in turn decrease performance.
This is only some short handbook knowledge as I haven't implemented
replication yet.
Greetings
Martin Johannes Dauser
On Mon, 2018-11-19 at 17:51 -0800, Daniel Miller wrote:
> I have a small but critical server that supports our group. As a
> single
> server - it's obviously a single-point-of-failure for lots of
> things.
> As I just experienced...again. It was a lot more fun building
> systems
> from components when I was younger...
>
> Previously 3rd-party hosted solutions didn't look attractive for
> several
> reasons...but I'm seeing prices now for cloud virtual machines that
> are
> stupid cheap. Even if they wind up being limited speed &
> availability -
> it would seem they'd be a lot better than nothing!
>
> So I'm considering having at least one backup server for various
> services - obviously that includes mail. So now I have to wonder
> about
> the backend. And while I think I'm reasonably current with
> networked
> file systems (not distributed or cluster) I haven't played with
> replication for a quite a while.
>
> For this particular usage (I'm envisioning two servers total) - is
> there
> a need/reason to use any form of networked/distributed/cluster file
> storage? Or would this be accomplished via "pure" Dovecot - dsync
> replication would keep things updated between the servers and
> director
> would handle the connections? So with identically configured SMTP
> servers, passing to the local LMTP agents, the file system would be
> "purely local" with no NFS or other interconnection?
>
