I have a windows server 2008 R2, I
have an Enterprise license
1) Do I need to activate windows
server on each hyper-v server? As if I
add a particular role for a server
i.e. IIS it will then prompt me for a
Web Server key for that hyper-v
server. The host server has a
If you want to maximize your dollar value, go with datacenter...you get unlimited (well up to 192 with current processors) licenses for VM instances with a per-processor license of Datacenter edition. You still have to purchase Client Licenses for any server that uses AD for user access outside of administration, but you're definitely saving on server licensing costs.
What's all the rave these days is buying a multi-socket, multi-core (BTW Windows Datacenter is licensed per socket not core) machine with a crap ton of RAM to virtualize your entire datacenter for example, check out this Nehalem based Sun Fire (up to 24 cores, and 256 GB RAM in a 2U machine)
The Datacenter SKU comes with a Volume License Key...although it does require activation, you won't exhaust activations as quickly as you will with non-VL keys. You also get downgrade rights so you can run any supported version of windows your heart desires.
2) Do I have to install and run an
anti-virus on each virtual machine or
will running just on the host server
3) Similarly with above, do Windows
updates need to be applied to each
hyper-b server or just the host?
Most anti-virus solutions need to be applied directly on the guest machines. (I would say all but there might be something I'm not aware of). Microsoft Forefront I believe has a per socket licensing plan that let's you pay a single price to cover all of your VMs (don't quote me on that but I do recall seeing this somewhere).
Windows updates need to be applied per guest as well...this is a good thing because it allows you to selectively apply updates (in case one or more might create conflicts with the software on a particular VM).
4) Are hyper-v snapshots backups
(images) than can be restored?
For backups, I would suggest actually making a backup of the full VHD. Snapshots are more or less a convenience feature to enable you to easily roll-back the state of your VM (great for lab or testing environments).