RE: Extended RAC:11G R2

From: Amit Verma (IT - Otterbase) <"Amit>
Date: Thu, 5 Aug 2010 09:32:28 -0400
Message-ID: <>

I implemented a 10gR2 extended RAC for a client. The sites were less than 20 miles apart; I believe Oracle supports up to a 100 miles (not sure on this). The storage was EMC SRDF sync between the sites, so no DG. As everyone has said, make sure the network can support the bandwidth.

The only benefit I could see in this configuration was you can achieve HA and DR in the same configuration without the use of Oracle standby and save on extra servers at the DR site.

HTH.   Amit Verma
Borders Group, Inc.  

-----Original Message-----

[] On Behalf Of Crisler, Jon Sent: Thursday, August 05, 2010 9:21 AM
To:;; oracle-l;
Subject: RE: Extended RAC:11G R2

You need to make sure that your link to the remote site has the capacity to support your workload. You need to be able to have low latency and high bandwidth- this tends to call for a link riding on OC-48 or better, which is a very expensive pipe.

-----Original Message-----

[] On Behalf Of Bobak, Mark Sent: Thursday, August 05, 2010 8:37 AM
To:; oracle-l; Subject: RE: Extended RAC:11G R2

Personally, I've never understood the whole idea behind extended RAC. What's the point?

Seems to me, you're taking an already complex technology (RAC), and adding another layer of complexity (the extended distance between nodes).

One of the more performance sensitive areas of a RAC configuration can be latency of the interconnect. Extended distance between nodes will only increase the latency. (You can't argue with the laws of physics.) What's the distance between sites? Also, what's the storage configuration going to look like? You going to have storage replicated at both sites?

And, finally, what's the (perceived) benefit?

Why do an extended RAC cluster? Seems to me, you could do a RAC at each data center, and do DataGuard between the sites. Any reason such a configuration would not be sufficient?

I've never worked with an extended RAC configuration, so, I don't have any first hand experience, but, in my view, it seems like a lot of added headache for very little (if any) benefit.

Hope that helps,


From: [] On Behalf Of Avadhani mys [] Sent: Thursday, August 05, 2010 6:05
To: oracle-l;
Subject: Extended RAC:11G R2

Hello Gurus,

Has anyone implemented extended RAC, please let me know the pro's and con's and any useful links would be really helpful.We are in the process of finalizing proposal to implement extended RAC.

Thanks in Advance




-- Received on Thu Aug 05 2010 - 08:32:28 CDT

Original text of this message