RE: Extended RAC:11G R2

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-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Crisler, Jon
Sent: Thursday, August 05, 2010 9:21 AM
To: Mark.Bobak@xxxxxxxxxxxx; avadhanimys@xxxxxxxxx; oracle-l;
oaugnetdba-on@xxxxxxxx
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-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Bobak, Mark
Sent: Thursday, August 05, 2010 8:37 AM
To: avadhanimys@xxxxxxxxx; oracle-l; oaugnetdba-on@xxxxxxxx
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,

-Mark
________________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx [oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Avadhani mys [avadhanimys@xxxxxxxxx]
Sent: Thursday, August 05, 2010 6:05
To: oracle-l; oaugnetdba-on@xxxxxxxx
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

--Avadhani

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