On 12/01/11 13:42, Jonathan Tripathy wrote:
On 12/01/11 13:36, Steve wrote:
-------- Original-Nachricht --------
Datum: Wed, 12 Jan 2011 13:47:00 +0100
Von: John Adams<mailingli...@belfin.ch>
An: postfix-users@postfix.org
Betreff: Re: Network Ideas
Am 12.01.2011 12:03, schrieb Jonathan Tripathy:
On 12/01/11 10:45, John Doe wrote:
From: Jonathan Tripathy<jon...@abpni.co.uk>
While your idea would work in HA mode, would that cause any problems
if both
postfix servers were used at the same time? (i.e. load balanced)
In fact I may be able to answer my own question by saying yes, it
would cause
a problem as you're not supposed to write to a DRBD secondary...
I saw some active-active DRBD howtos; but they used filesystems
likeOCFS2 or GFS
and such...
http://www.sourceware.org/cluster/wiki/DRBD_Cookbook
But I am no expert...
JD
If I used a nfs cluster, I could use both postfix server at the same
time, couldn't i?
these questions you should really ask in the heartbeat/drbd
mailinglist(s).
Just one hint: think about complexity in an active-active cluster
running ocfs2 and mail. Think about file locking.
Building this is one thing. Managing the unexpected afterwards is
another thing.
I run a two node mail server using GlusterFS with replication. It is
ultra easy to setup. File locking in mail environments is no big
issue. Mostly mail arrives on one of the mx nodes, gets processed and
then passed to the delivery agent, the delivery agent then saves the
mail (in my case maildir format) into the final destination. In the
whole processing there is almost no locking involved since the mail
saved in the maildir has an unique number and that alone mostly
avoids the need for locking. The POP/IMAP server does then indexing
and this is the place where locking is/can be involved. But a good
IMAP/POP server can handle that (dovecot can).
The whole storage part works so well that I often forget that it is
clustered. The good thing about GlusterFS is that I can add as many
active nodes as I like.
The only part where you have to take care about a clustered mail
servers or a n-node mail server setup is more the other things that
you glue into the mail server. Things like greylisting, antispam,
mailing list software, etc... This kind of stuff requires to be
cluster aware. The storage is the lesser problem IMHO.
Thanks Steve, excellent info
As for the antispam, greylisting and av things, they will be on
different servers which are related to the cluster, so I think I'm
good there.
As for the GlusterFS, I take it this would replace DRBD, Heartbeat and
NFS in my proposed setup? Have you got any good links that you would
recommend to setting up such a setup?
Thanks
Also Steve, how do you find performance of GlusterFS? Are both your
Postfix/Dovecot servers GlusterFS clients? Reading around, a lot of
folks are having performance issues with GlusterFS. But they are over a
year old posts though...
