On 2014-02-11 16:04, Mark Jenkins wrote: 

> It would suck if
someone used the VM server as follows -- install one 
> 
> crippled
Windows guest and then cloned it again and again... because 
> each
guest OS instance takes up dedicated RAM. Would. Not. Scale.

For KVM:
Kernel Samepage Merging.
https://www.kernel.org/doc/Documentation/vm/ksm.txt 

Or, for VMware:
http://pubs.vmware.com/vsphere-4-esx-vcenter/index.jsp?topic=/com.vmware.vsphere.resourcemanagement.doc_40_u1/managing_memory_resources/c_sharing_memory_across_virtual_machines.html
and
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1021095


Most VM systems actually handle this quite well. 

Turning up a bunch
of WinXP/Win7 VMs that are all running the same software actually chews
up a *lot* less memory than you'd expect because of this feature.


Using Windows Deployment Services can turn re-deploying a lab-ful of
XP/W7 VMs into a (relatively) easy task, although that does require a
Windows Server. Building a pre-install environment for that Windows
Server based on the 180-day eval media can turn deploying a lab into a
push-button operation that takes about 4-5hrs to deploy (mostly iowait).
I will readily admit, however, that getting to that point is probably
60-80hrs of work :-). (And, so we're clear - that's 60-80hrs of work
that I am not going to be doing!) 

Also, logging multiple users into a
single Windows Server isn't anything like UNIX - that's a Windows
feature called Terminal Server, which requires separate, additional
licensing, and requires significant expertise in Terminal Server to
configure correctly. You can't just blindly install apps the way you
usually do, you have to jump through lots and lots of hoops to ensure a
common app works correctly for all logged-in users. 

-Adam 

 
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