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Re: [Linux-cluster] Postfix active/active mail cluster

As I said, I wouldn't bother with LVS, but there's no harm in doing so.
It just means you either have to use a fail-over pair of load balancers in front of your mail cluster, or have each machine in the mail cluster act as a fail-over load balancer and distribute connections to all the machines (including itself). It just sounds like an unnecessary complication.

And the outgoing mail going through a smart-host is a bottleneck on a properly tuned system - it means that you have multiple machines to handle incoming mail, but only one to handle outgoing mail. An "equal peers" solution is far more scaleable.


Mehmet CELIK wrote:

Thanx for information. Just, I said be carrefull. My organization is below.
LVS -> 78.189.X.X {25,143}
MAIL1 -> 78.189.X.X {25,143}
MAIL2 -> 78.189.X.X {25,143}
MAIL3 -> 78.189.X.X {25,143}
SMTPGW -> 78.189.Y.Y {All outgoing traffic} sh $ host -t ptr 78.189.Y.Y
Y.Y.189.78.in-addr.arpa domain name pointer xxxx.exampledomain.com

Mehmet CELIK

 > Date: Sun, 23 Mar 2008 01:33:36 +0000
 > From: gordan bobich net
 > To: linux-cluster redhat com
 > Subject: Re: [Linux-cluster] Postfix active/active mail cluster
 > Mehmet CELIK wrote:
 > >
 > > Hi, of course, you can do this. so, each node on *LVS will respond
 > > active.
 > Not much point - DNS load balancing works just fine for a mail server.
 > Or you can use the cluser resource manager to migrate the IP of a downed
 > node to another node.
 > > But, this is different from storage subject. The IMAP don't be
> > problem. But, the SMTP can be a problem. Because, you have dynamic ip on
 > > the RBL checks. For this, you must use smtp gateway. All outgoing smtp
 > > traffic must be from a single IP.
 > I don't remember anyone saying that dynamic IPs are used. Just because
 > the mail cluster has a different IP for each host doesn't make them
 > dynamic. RBLs that block dynamic IPs largely only block
 > dial-up/broadband dynamic IP ranges, and I don't thing the original
 > poster ever suggested that this is the sort of range the mail cluster
 > he's building will be on.
 > There is no RFC that states that all mail from a domain must come from
 > one IP. Having multi-homed mail servers with multiple IPs is perfectly
 > RFC compliant. Google do it, for example, as do many other mail service
 > providers. The main issue with this is that there are people who use
 > fundamentally broken anti-spam measures like greylisting, which fall
 > over flat on their face when consecutive delivery attempts come from
 > different IPs. Breaking your mail cluster scalability to work around
 > someone's broken mail system is, IMO, not the correct solution.
 > However, as I mentioned in the other post on this thread, if you make
 > the mail spool local rather than shared, then the outgoing mail will not
 > bounce between the nodes - it will remain on the same node until
 > successfully delivered (or bounced). This works around the problem of
 > broken mail systems.
 > Gordan
 > --
 > Linux-cluster mailing list
 > Linux-cluster redhat com
 > https://www.redhat.com/mailman/listinfo/linux-cluster

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