[Linux-cluster] Postfix active/active mail cluster

[Gordan Bobic]

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.

Gordan

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
> Istanbul/TURKEY
> 
> 
>  > Date: Sun, 23 Mar 2008 01:33:36 +0000
>  > From: gordan at bobich.net
>  > To: linux-cluster at 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 at redhat.com
>  > https://www.redhat.com/mailman/listinfo/linux-cluster
> 
> 
> ------------------------------------------------------------------------
> In a rush? Get real-time answers with Windows Live Messenger. 
> <http://www.windowslive.com/messenger/overview.html?ocid=TXT_TAGLM_WL_Refresh_realtime_042008>
> 
> 
> ------------------------------------------------------------------------
> 
> --
> Linux-cluster mailing list
> Linux-cluster at redhat.com
> https://www.redhat.com/mailman/listinfo/linux-cluster