Windows Server 2008 R2 base o/s size
I am creating Windows Server 2008 R2 VM and was wondering if anyone had an estimate on the base size of the o/s when installed?
I need to decide if I am think/thick provisioning it and need an estimate for the SAN space!
Microsoft recommends 20GB for 32bit and 32GB for 64bit for Windows 2008 (not R2), but they don't list the disk requirements for R2. However, in practice, I've found these numbers are way under what I'd even consider a recommendation. I'd go with a minimum of 50GB.
We built a handful of 2008 servers with 20GB c: partitions, and simply enabling IIS, and registering a few DLLs that were required for our site to work quickly made 20GB a difficult size to live with. We ended up resizing the partitions up to 40GB, before we realized even that might be a little too small.
As Chris S hinted, the answer is entirely subjective to what you are doing with it, what features you have enabled, what roles you're working with, and what version of R2 you have.
The .vhd (once decompressed) for the evaluation Windows Server 2008 R2 Virtual Machine (get it here) is 6.5GB.
As this is the OS + Hyper-V Integration (and the latter is small) this should give an absolute lower limit.
While Microsoft recommend 20GB for the Base OS I would recommend from experience that you give it 40GB for the OS. Unfortunately Windows uses the C: to install part of applications even if you tell it to install on the other drive. This should give you enough scope to grow with your apps and hotfixes.
The nice thing with 2008R2 and 7 is that you can shrink/extend the volumes after installation, so if you find you need more or less, you can just go to Disk Management and right-click on the OS volume and choose accordingly.
That said, I always start with 20gb and then adjust as needed. Hopefully you'll be able to get disk space savings through other ways like De-Dupe.