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April 30, 2009



I'd like to offer a clarification.

"Parsing a query has to do with issues of table statistics, query syntax, hints, and the like."

With Oracle 8i and earlier, that was true. Starting with Oracle 9i, Oracle can use system statistics, such as I/O and CPU performance and utilization as input to the query optimizer. These things could be affected by being deployed in virtualized hardware.





Your comment is technically true but somewhat pedantic. I did not point out the painfully obvious: Everything eventually has to do with the operating system. And I did know that the cost based optimizer was adopted in version 8, and the rule based optimizer was used previously.

On the issue of whether virtualization has to do with a particular support issue, it is a matter of degree. If a query is doing a full table scan instead of using an index, it is theoretically possible (albeit astronomically unlikely) that it is at the very edge of the decision point, and the OS statistics returned by the virtualization layer has shoved it in one direction or another. But that would be a case in which the use of the index was a close call, and the query performance would be almost the same either way.

It is far, far more likely that a gross event like using a full table scan which causes the query to take far longer than it should is due to faulty statistics (yes these are still very much used after 8i) rather than virtualization. Or some other issue with the query execution engine may be a factor.

If I simplified this unduly, then I apologize for the mis-communication. I assumed that my reader would have the ability to extrapolate.


Iain Mobberley

I wondered if you can now re-consider the future of RAC clusters on VMware now that vSphere is available in the market, specifically with the regard of VMwareFT?

I assume that this further weakens Oracle's position with regards their own "HA" functionality versus what is now available from VMware?


Response by TOSG:

We have completed testing of FT in the context of our virtualized solutions. FT does work with Oracle database servers. However, it is presently limited to only one vCPU, which limits scalability. For our testing, we typically use 4 vCPUs per VM.

I think the single vCPU restriction will eventually be expanded. At that point, I think FT will be more useful. In the meantime, I recommend it for small database server workloads which can fit onto a single vCPU.


Thank you for parsing the language in the metalink article. I am an Oracle EBS consultant and many customers were scared to migrate to vmware because of the Oracle support policy even though as you very clearly explained there is no technical reason for non-RAC environments.



Hello, I am somewhat baffled by one aspect of the Oracle/VMware conundrum: Everyone focuses heavily on the technical aspect (which is obviously important) but there is a far more problematic aspect (unless I missed something important): money.
Oracle licensing requires you to license every core physically present on your hypervisor (whatever technology you use except of course Oracle VM).
For me this represents a far more efficient deterrent than the support issue. Am I wrong ?


Yes, you are wrong. Oracle licenses the software on a physical core basis, not a virtual CPU basis. So 8 VMs with 1 Oracle instance each (8 total) running on a physical server cost exactly the same amount for Oracle licensing as running 1 database instance on a physically booted configuration. Assuming your utilization of the physical box is significantly less than 100% (which is true the vast majority of the time), virtualization can save you money, as you can improve utilization and thus lower cost per transaction. This is one of the core value propositions of VMware virtualization in general. It is simply amplified in the Oracle space, because Oracle is a tier-1, relatively expensive piece of software.

Cheap Computers Canada

The reasons for vm ware are political and thsi is what stopping form accepting it.

Michael Wirz

If you use Oracle on VMware you have to license all CPU Cores in your machine:
VMWare Host ==> 64 Cores
VM with Oracle ==> 4 cores
Then you have to license 64 cores!!! not only the 4 cores of the Oracle VM.


True, but that was my the point of my comment that you must isolate all Oracle VMs to their own set of ESX servers. That way you are running Oracle on all 64 cores.




Hello, excelent article, i have a questiong about the Oracle Licensing, if i have VMware vSphere in a Two Host for HA, each ESXi host have a two processors and each processors have a 6 cores, if i put the Oracle in a VM with only 4 vCPU, i need to licensing all cores in the physical server?, or i can isolated the VM and only licensing the 4vCPU(cores in use for the VM with Oracle), thank you for your help... if posible have VMware HA with this same licensing?

Price Acomplia

Hello. Good article )


Hi, good article - still not sure about the licencing aspects though - as I understand it, a single Oracle VM with access to 4 vCPUs on a 4x4Core (16 Core) Host will require an Enterprise Licence @ $40K and a CPLF of 0.5 for all 16 cores - ie: $40K * 16 * 0.5 = $320K
What about if I have 5 Oracle VMs (each with 4 vCPUs) on the same host - will that require each VM to be licenced for the capacity of the host? ie: 5 * $320K = $1.6M

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disclaimer: The opinions expressed here are my personal opinions. I am a blogger who works at EMC, not an EMC blogger. This is my blog, and not EMC's. Content published here is not read or approved in advance by EMC and does not necessarily reflect the views and opinions of EMC.