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Getting Close to Physical - Database Weekly (Nov 8, 2008)

By Steve Jones,

This past week there was a report that tested the performance of Oracle on a physical machine on a virtual machine under Hyper-V on the same hardware, or essentially the same hardware. There were two identical machines and one ran Hyper-V, with slightly less than the total physical hardware defined on the VM. The hardware on the physical machine was then lowered to match the VM.

What was amazing with this test is that the performance of the VM was very, very close to that of the physical machine. In the OLTP test, there was slightly more CPU (95% to 92%) and memory (46% to 44%) used, and the average TPMs was very close (16,916 to 17,071) on the virtual database server as compared to the physical server.

The report is worth reading if you might look at virtualizing SQL Server and it shows just how close Hyper-V performance can be. I would hope to see VMWare and other vendors publishing these types of comparisons as they can help show the possibilities on a well configured system.

The important thing to emphasize here is that there isn't any consolidation taking place here. In other words, no other VMs are running on the physical box that is hosting the database server, which is how any heavily used VMs ought to be configured. The VM configuration and load for file servers is not the same as database servers, and it's important that managers that run virtualized shops are aware of this.

Is virtualization a good idea? I think it's hard to argue against it in any environment. With reports like this one from Rockford Construction, it's starting to make more and more sense to start virtualizing with all new servers that you purchase. More and more companies are realizing cost savings and that will translate into competitive advantages if you don't start to match them.

I've seen reports that anywhere from 50-80% of IT budgets is spent just keeping things going, not on new projects. That means if you aren't efficient, you are either not spending as much as your competitors on new projects that can help your business, or you might be skimping on things and perhaps not staffing enough people or paying them enough. Either of which can make you much less competitive.

As costs rise in data centers, it becomes important to think about virtualization. This is a one time cost savings, but it's important. And as this report shows, even database servers can be virtualized without too much of a performance penalty.

Steve Jones

The Pick of the Week

This week I saw some interesting discussions on transaction logs and recovery. Kalen Delaney had a great blog post that I think you should check out on When is FULL Recovery not Really FULL Recovery.

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