Hi Stan,

> 
> I think Victor meant "not" a Postfix issue.  If you
> want to build a mail
> store cluster over a WAN link, start your reading here:


> 
> http://www.drbd.org
> http://sourceware.org/cluster/gfs/
> 
> The combination of these will allow you to accomplish your
> cluster goal.
>  Depending on the aggregate write bandwidth of your MTAs
> and delete b/w
> of your POPD, you may need a site-to-site link of anywhere
> from 10Mb/s
> to 100Mb/s, or maybe even more.  If your two servers
> are located in
> buildings on the same campus and connected via 100/1000Mb/s
> ethernet
> then this solution will work very well.  If your two
> servers are located
> in two internet colocation facilities and your b/w is
> limited to 10Mb/s
> or less, RTTs are unstable, etc, then this solution may not
> work well
> for you.  Mirroring a disk over a network requires a
> stable quality network.

I agree with your point.
the above solution should work well if the active/active server
are located in the same location.

for the machines in different data center, there is no guarantee of speed.

also, making the server run in a different data center is fail-over protection 
solution.

using rsync is a way to synchronize the storage. 
however, multiple MX record only works well if pointing to servers
in the same data center sharing the same storage for imap.

thus, a valid solution is to change the IP address of imap server 
when failover is required. but the dns propergation might take up
to three days. is there a better alternative? 


guess it is something beyond postfix to handle. not sure how postfix users will 
handle such an issue?

Thanks.

Peter




    

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