32 or 64 bit guest operation system

[Bas16723]

We are searching for a while now and can't find any real good answer at an official statement.

We have a couple of VMWare vSphere Hypervisor (ESXi 4.1) servers running. The host is running 64 bit (no other way possible) and at this moment we have 32 bit guests. We are using about 512 MB of RAM for each VM, so for that reason we do not need 64 Bit.

Now some people in the organisation are saying: "64 bit as guest is better, because the host is 64 bit. And then there is no conversion needed for the CPU". Other people think this is crap.

So, is there an (official) statement from VMWare which is the best choice?

[DSTAVERT]

The decision to use a 64bit OS should be made on the application(s) and memory requirements. If you have a 32 bit application and low memory requirements there is no reason to use 64bit. Whether a 64bit OS works as well or better in a particular situation should based on testing.

[AndreTheGiant]

There isn't an official position from VMware.

As written choose it based on your OS/applications/services requirements.

Some other notes:

* 64 bit versions usuall have a bigger memory and storage footprint

* 64 bit platforms have more hypervisor overhead

* standardize the platform and the OS will make the hypervisor memory management better (for example for TSP)

Andre

[JimKnopf99]

It only depends on your need.

The older MS Server Systems are going out of Support.

That could be one reason to update to x64.

But VMware doesn´t matter what OS you use.

Frank

[Lessi001]

Hi,

it is up to you - but if I were you I would try to use the latest operating system. If you use Microsoft Server this would be 2008 R2 - only available in 64 bit (if supported from your application).

Regards

Andi

[Bas16723]

The question is not related to Microsoft in our case. We use a mix of Linux and Microsoft, and in this case Linux will be the main operating system we are talking about.

Too bad that VMWare has no official statement, I need to convince the pro 64 bit people why not if there are good reasons for.

[AndreTheGiant]

One reason could be uniform the platform.

IMHO, for Windows I use Windows Server 2008 R2... so this is a x64 platform (without any choice).

But for Linux, most of mine VMs are quite small (max 2 GB of vRAM), so there is really no reason to use the 64 bit version.

Could be different if you need some Linux box with x64 (for example for DB)... in this case uniform all Linux VM to the 64 bit platform could be a good idea.

Andre