[Dovecot] nfs director

[Edward avanti]

On Fri, Aug 27, 2010 at 3:28 PM, Brandon Davidson <brandond at uoregon.edu>wrote:

> Noel,
>
> On 8/26/10 9:59 PM, "Noel Butler" <noel.butler at ausics.net> wrote:
>
> >> I fail to see advantage if anything it add in more point of failure,
> with
> >
> > i agree with this and it is why we dont use it
> >
> > we use dovecots deliver with postfix and have noticed no problems, not
> > to say there was none, but if so, we dont notice it.
>
> We might be a slightly larger install than you (60k users, mail on FAS 3170
> Metrocluster), but we have noticed corruption issues and the director is
> definitely going to see use in our shop. We still use Sendmail+procmail for
> delivery, so no issue there... but we've got hordes of IMAP users that will
> leave a client running at home, at their desk, on their phone, and then
> will
> use Webmail on their laptop.
>
>

Sendmail and procmail? This mean you use mbox? This always bad for NFS
anyway




> Without the director, all of these sessions end up on different backend
> mailservers, and it's basically a crapshoot which Dovecot instance notices
> a
>

backend is not problem. it front end it where mail arrives, these are server
we should be able turn off indexing, other front end type server for pop3,
can have index on since no multi login allowed




> new message first. NFS locking being what it is, odds are an index will get
> corrupted sooner or later, and when this happens the user's mail
> 'disappears' until Dovecot can reindex it. The users inevitably freak out
> and call the helpdesk, who tells them to close and reopen their mail
> client.
> Maybe you're small enough to not run into problems, or maybe your users
> just
> have lower expectations or a higher pain threshold than ours. Either way,
> it's unpleasant for everyone involved, and quite easy to solve with the
> director proxy.
>
> Timo has been saying for YEARS that you need user-node affinity if you're
> doing NFS, and now he's done something about it. If you've already got a
> load balancer, then just point the balancer at a pool of directors, and
> then
> point the directors at your existing mailserver pool.
>
> <shameless plug>
> For health monitoring on the directors, check out:
> http://github.com/brandond/poolmon
> </shameless plug>
>
> -Brad
>
>