32 Bit vs 64 Bit

[etieseler]

Question for the guru's:

If given the option to run a 64 bit VM or a 32 bit VM what should I choose given the following scenario:

Guest OS is Windows Server 2003 running SQL 2005 with 2 vCPU's and 1024 MB of RAM (possible increasing).

I am using VI3 (ESX3.0.2) on Xeon 5160 CPU's.

I probably will not hit the 3GB limit so I know that will not be a selling point to use 64 bit, but are there any other compelling reasons?

Will performance be better / more efficient in the VM or on the ESX host by using 64 bit instead of 32 bit?

I am trying to decide whether I should consider moving this server to the 64bit versions of W2k3 and SQL or remain on the 32 bit versions.

Thanks!

-Ed

[jlauro]

In general, if the VM isn't going to have more than 4GB of memory, 32 bit is better.

However, if you think you will start out with <4GB, but possibly upgrade it in the future, you might be better off with 64-bit so you can change in the future easily and the overhead of running 64-bit isn't that large so it doesn't hurt much to be non optimal... (Hurts more to run 32-bit OS and have it use more than 4GB of RAM).