-------- Original-Nachricht -------- > Datum: Wed, 12 Jan 2011 13:56:37 +0000 > Von: Jonathan Tripathy <jon...@abpni.co.uk> > An: postfix-users@postfix.org > Betreff: Re: Network Ideas
> > 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... > Performance was often a problem in the past (however you still can have very bad performance with current GlusterFS software). I often see people that compare single NFS server connected with GbE and n-node GlusterFS connected with GbE and then they complain that GlusterFS is slower. Off course it is slower if you compare that way. GlusterFS will not automagically make your storage faster. If speed is an issue for you then add NICs to the system and bundle/team them and increase caching. In my experience the speed is good enough for what I get additionally (the confidence to not have a single point of failure, the possibility to have more then two active nodes (serving as many clients as I like (in this case a client can be a mail server with just the blank OS and postfix and the GlusterFS client process accessing the storage as if it would be local)), additional flexibility, easy management of storage, capabilities to grow endless with storage, etc). -- NEU: FreePhone - kostenlos mobil telefonieren und surfen! Jetzt informieren: http://www.gmx.net/de/go/freephone
