Replicate to more than one replica?

David Korpiewski davidk at cs.umass.edu
Tue Jun 6 16:04:16 EDT 2006



Wesley Craig wrote:
> On 06 Jun 2006, at 13:56, David Korpiewski wrote:
>> Is it possible for one master to rolling replicate to more than one 
>> replica?   I'd like to have one master and two replicas.
> 
> Can you share why you're interested in two replicas?
> 
> :wes


Sure.

We have one master with two replicas.

The greatest fear here is losing any new email.  So we came up with a 
concept of having a master, an "active replica" (which will take over 
from the master if the master dies), and a "silent replica".

When the master goes away, the "Active replica" becomes our primary mail 
server, the "silent replica" just sits there and does nothing.

When we bring the master back up we make sure cyrus is turned off. Then 
we do a full mailstore diff on the original master and the silent 
replica.  This will give us a list of the email that was not propagated 
when the master went down.   This diff should be showing us the email 
that is not on the current mail server based on the assumption that the 
two replicas were being updated at the same time.  Then we just find a 
way to send over that email and we should be all set.

This is technically easier than trying to reconstruct from the logs what 
was not propagated, especially since I've found the log files to be not 
very informative even in verbose mode.

-David


-- 
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David Korpiewski                     Phone: 413-545-4319
Software Specialist I                Fax:   413-577-2285
Department of Computer Science       ICQ:   7565766
University of Massachusetts Amherst
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