On Thu, Apr 11, 2013 at 1:44 AM, Shaun Thomas <sthomas@optionshouse.com> wrote:
> On 04/10/2013 11:40 AM, Fujii Masao wrote:
>
>> Strange. If this is really true, shared disk failover solution is
>> fundamentally broken because the standby needs to start up with the
>> shared "corrupted" database at the failover.
>
>
> How so? Shared disk doesn't use replication. The point I was trying to make
> is that replication requires synchronization between two disparate servers,
> and verifying they have exactly the same data is a non-trivial exercise.
> Even a single transaction after a failover (effectively) negates the old
> server because there's no easy "catch up" mechanism yet.
Hmm... ISTM what Samrat is proposing can resolve the problem. That is,
if we can think that any data page which has not been replicated to the standby
is not written in the master, new standby (i.e., old master) can safely catch up
with new master (i.e., old standby). In this approach, of course, new standby
might have some WAL records which new master doesn't have, so before
starting up new standby, we need to remove all the WAL files in new standby
and retrieve any WAL files from new master. But, what's the problem in his
approach?
Regards,
--
Fujii Masao