Yesterday the Windows team disclosed some information on what you can expect for Service Pack 1 for Windows 7 and Server 2008 R2.  While there are no new features set for Windows 7 SP1 there is a change to XP Mode available for Windows 7 Professional and up.  Until now your computer needed to support hardware assisted virtualization for XP Mode to run but that has changed.  XP Mode will now run on all CPUs!  This is great for those people with 2+ year old computers that have the horsepower to run Windows 7 but don’t have the CPU extensions, or the BIOS support to enable hardware assisted virtualization.  You can get the bits here..

The more exciting news (to me anyway) were the announcements around Server 2008 R2 SP1.  There are two big new features that will be released with this service pack…

  • RemoteFX
  • Dynamic Memory

RemoteFX is a technology (from the Calista acquisition in 2008) that give remote workers using Remote Desktop Services (aka Terminal Services) the full Windows Aero desktop environment, support for full motion video, Silverlight apps and 3D applications.  You’ll be able to extend the same experience to users with thin clients accessing a VM on Hyper-V R2 as they would get on a full featured PC.

Dynamic Memory is a technology that will allow you to dynamically allocate memory to VMs running on a Hyper-V R2 host.  Now those of you with experience with ESX might think this is like memory overcommit but it is different.  In a nutshell both technologies allow you to assign more memory to your VMs than the host has.  For example I can start 5 VMs each with 4GB of RAM eventhough the host only has 16GB of RAM.  Memory Overcommit is different in that it uses paging files for that extra address space.  As you are aware paging has a negative impact on performance.  I am simplifying but that’s basically it.

Today, on a Hyper-V host when you assign a VM 4GB of memory and start it, it locks out the 4GB of address space on the host for that VM.  Now that VM might only be utilizing 1GB meaning that the other 3GB is essentially idle until the VM requires it.  With Dynamic Memory we will still assign the VM 4GB of RAM however it will only lock the address space the VM is utilizing leaving the rest available for other VMs.  When a VMs memory utilization increases, it will draw from that pool and when memory utilization decreases it will release it back into the pool.  Again I am simplifying things but that is how it works in a nutshell. 

What this means is that you’ll be able to use the physical memory in your Hyper-V hosts more efficiently without impacting performance in your production environments.

You can see a demo of RemoteFX and find out more about these changes at