I certainly believe that it is possible, especially in highly parallelized environments, for performance to get gated at the speed of the slowest node. However, I definitely have customers in OLTP environments where they added faster nodes (i.e. 4 nodes at 2 GHz, 2 nodes at 3.2Ghz), and saw the overall throughput improve, and saw the two new nodes with a higher number of sessions, but comparable SQL response time. I don't know enough about the lock hashing to say for certain, but lock management is definitely a high-priority event, so assuming your newer nodes indeed take up a proportionately higher number of sessions/queries, lock management should scale appropriately. This would be an interesting benchmark factory experiment. I might have some free time and free hardware late next week to give this a shot. Thanks, Matt > -----Original Message----- > From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] > On Behalf Of Bobak, Mark > Sent: Thursday, July 23, 2009 5:42 PM > To: Jon.Crisler@xxxxxxx; 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, > > -Mark > > -----Original Message----- > From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] > 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. > -- > //www.freelists.org/webpage/oracle-l > > > > > -- > //www.freelists.org/webpage/oracle-l > -- //www.freelists.org/webpage/oracle-l