Here is the spoiler -- don't do Windows 7 x64 for VDI.
Now let's talk about why. First, I'm going to give credit to Brian Madden's Blog, he mentions this also, and he is exactly correct. Windows 7 x64 uses around 200MB more memory than the x86 version. If you multiply this by the number of VDI users, it adds up quickly. (1000 desktops x 200MB equals 2 TB more memory). For a project I'm working on this equated to a requirement for 8 more servers because of x64.
Now, let's add to that some additional recommendations. VMware's Server Storage Sizing Guide suggests the following for Windows 7 x64:
- 2GB of memory
- 2 vCPUs
- an additional 4GB of storage space.
Contrast this with the requirements for Windows 7 x86:
- 1GB of memory
- 1 vCPU
- no additional storage.
This effectively cuts your VDI capacity in half, and increases the storage requirements.
Do you need the ability to address more than 3GB of memory?
How many of your apps are 64-bit?
If you run XenApp, as I do, can you deliver the apps to the user via XenApp?
Who are your users? How really needs 64-bit?
These questions have the potential to change your direction for VDI. VDI is not the same as physical. The containers (HW, VM, etc) are different and should receive an optimized OS designed for the container.
Brian's article mentions that 29% of the deployed desktops are Windows 7 x64, and 25% are Windows 7 x86. If this is truely the case that there are more x64 desktops than x86 desktops, then I think it is time to go back and revisit the assumptions and reasons for deploying x64 VDI.
Personally, I want fast for as many people as possible. I don't want the VDI experience to be slower for users. Nor do I want the business to take on an unnecessary expense without really needed that expense. In my experience and opinion VDI (done well) makes migrating to "newer" desktops easier and faster. Let's just do it intelligently.