Re: asynchronous multi-master replication

Hi Stalin,

If your'e on 10g, have you thought of implementing streams instead of multi-master replication?

I've implemented replication in 9i using MMR on a couple of Solaris servers. Although it's fairly stable, when things go wrong, they really go wrong.

One example I can give is when we accidently deleted about 10 million rows from a table that was part of our replication group. It hosed up the entire replication from one site to the other. Reason being that the deftran queue just could not handle that many transactions in a single DML. The transaction just sat there trying to propagate to the other site.

We tried clearing out the queues, shutting the database down etc, but we were unable to resolve the issue. It was finally resolved after we issued a TAR to Oracle.

Now I haven't used streams yet, but reviewing the docs, it appears to be implemented in a much more scalable manner. In a nutshell, the redo logs are scanned for DML/DDL and I believe the change vectors or records are transferred to the replicated site and applied there. It's not trigger based like MMR.

I'd suggest you look into Streams rather than Multi Master Replication. I believe you'll have fewer issues.

BTW, when it was working, we had no problems with performance. The two sites always stayed in sync. This was on an OTLP accounting type database.

Oh and also, DON'T use OEM to try and manage the thing. It'll just hang as well. Their are plenty of scripts and articles on Metalink to help you get by w/out OEM.

hth

--
mohammed
 

--- Stalin <stalinsk_at_gmail.com> wrote:



> Hi All,

> 

> We have a requirement to build an environment with 2

> databases running

> on two different locations with same set of

> applications running on each site.

> Apparently both database should be in sync all the

> time. After reading

> the doco, this requirement clearly begs for

> Asynchronous/Synchronous

> multi-master replication.  Don't ask me why this

> needs to be done from

> two different locations, that's part of SLA's.

> sometimes, SLA's make

> things more complex!

> 

> Can anybody share your experience in terms of

> performance/scalibility

> in a two way multi-master replication.

> 

> Configuration we are looking at for now is --

> 

> 4 proc, 4g mem,  15 (15k rpms) * 36 G on a raid 10,

> oracle enterprise

> edition (10g)  -- per site.

> 

> Thanks,

> Stalin

> --

> http://www.freelists.org/webpage/oracle-l

> 




		
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