RE: RAC - mix Intel and AMD in same cluster ?

From: Crisler, Jon <>
Date: Fri, 24 Jul 2009 12:08:44 -0400
Message-ID: <56211FD5795F8346A0719FEBC0DB067504A7B385_at_mds3aex08.USIEXCHANGE.COM>

Interestingly enough, the hardware we have is identical to yours. One of the things I am considering is upgrading the AMD Opterons from dual core to quad-core, but the dual core run at 3 ghz while he quad-core is only 2.4 ghz. So I have to look at other things like L1 and L2 cache, cache speed etc. and see how they compare in various benchmarks.

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

[] On Behalf Of Bobak, Mark Sent: Thursday, July 23, 2009 5:42 PM
To: Crisler, Jon; oracle-l
Subject: RE: RAC - mix Intel and AMD in same cluster ?

Hi Jon,

I had a similar concern recently, as we have a 3-node cluster of DL-585 G2s, and we were looking at adding two DL-585 G5s. The advice I got was that it may not be the best idea. Certainly, it will work, that's not the issue. And the question isn't really AMD vs. Intel, it's more about the CPU capacity of the newer nodes vs. the older nodes, and how many cores you're running, in terms of the number of CPU licenses. The issue is that, due to the way that RAC works, the performance of the newer nodes will be gated at the performance of the older, slower node. So, in our case, we've got 3 G2s w/ 4 dual core CPUs, and we were looking at adding 2 G5s with 4 quad-core CPUs. Due to the extra licensing cost of the two newer nodes, and the limited performance of the nodes when in a cluster w/ slower performing nodes, it's actually cheaper to get 3 new G5s and re-purpose the G2s for something else.

The reasoning behind why faster nodes in a cluster are gated to the performance of the slowest node, is that all nodes potentially participate in any SQL execution, even if it's not parallel. That's because lock mastering of data blocks is hashed to all the nodes. So, as soon as one of the slower nodes starts having CPU problems, lock management will suffer across the cluster, and everybody slows down. So, even though you may have a couple of nodes capable of much more CPU load, their performance suffers due to the fact that they must participate in the cluster, and the cluster is limited by the slowest node.

Hope that helps,


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

[] On Behalf Of Crisler, Jon Sent: Thursday, July 23, 2009 4:54 PM
To: oracle-l
Subject: RAC - mix Intel and AMD in same cluster ?

Has anybody here built or upgraded a 10g RAC cluster using a mix of both Intel and AMD processors ? We have an existing 3 node RAC cluster, RH Linux 4 with AMD Opteron 3 ghz dual core cpu's. It is being considered to add a 4th node but with Intel CPU since the servers we used ( HP DL 585 G2 ) are no longer available new. Any thoughts in mixing Intel and AMD processors in the same cluster ? We are also looking at upgrading the existing processors from dual-core to quad-core, but the quads seem to max out at 2.4 ghz while the duals go to at least 3.2 ghz. Obviously OS and Oracle will stay same version, but we might be forced to use Intel to add additional nodes, assuming it even works.


-- Received on Fri Jul 24 2009 - 11:08:44 CDT

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