We ran some tests over a year ago (and a couple of ESX versions) to try and judge the VMware overhead. We had identical boxes and had one piece of hardware hosting a single VMware Linux host and the other running only Linux. We found the overhead could be as much as 25% for certain test jobs. There could have been a lot of different issues with our tests though, as it wasn't really scientific. It is promising to see that others are seeing the overhead in the 1-5% range. I would really like to try this type of test again with Oracle's Real Application testing in 11gR2 That being said, I think VMWare is making fast progress and I would not be surprised if 5 years from now all of the systems our group supports runs VMWare by default (even for dedicated VMWare hosts). From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Allen, Brandon Sent: Wednesday, April 14, 2010 3:14 PM To: Jon.Crisler@xxxxxxx; oracle-l@xxxxxxxxxxxxx Subject: RE: Anyone Running Oracle on VMWare? Our production DBs run on dedicated VMWare hosts, so there is no contention with other virtuals. But, I believe VMWare has functionality to restrict the resource usage for each virtual host in order to prevent the kind of problems you're talking about. I'm not a VMWare admin, so I'm not sure on exactly what functionality is available or how well it works, but have you (or your VMWare admins) looked into it? I haven't found the overhead of VMWare itself to be very significant - maybe 1-5%, which could be significant if you're pushing your hardware to the limit to begin with, but in that case you probably need better hardware (or tuning to lighten the load) anyway. From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Crisler, Jon 1) Performance can be variable- depends on the load of the other guests, and vmware itself has significant overhead. We discourage putting production databases on vmware due to this issue. It can be difficult to tune Oracle on vmware due to the effect of other guests. ________________________________ Privileged/Confidential Information may be contained in this message or attachments hereto. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of this company shall be understood as neither given nor endorsed by it.