Hot Memory Resize with Windows 10

One of the features that was introduced in the Technical Preview (and later builds) of Windows 10 (and Windows Server) is the ability to resize the memory of virtual machines while they are running.

In Windows Server 2008 R2 SP1 we introduced the Dynamic Memory feature that allows Hyper-V to rapidly respond to the changing memory needs of the virtual machine, adding and removing memory as needed.  In Windows 10 we are augmenting this by allowing you to manually adjust the memory on virtual machines that have not been configured with Dynamic Memory.

To do this, you just need to change the memory as you normally would through the user interface or PowerShell – and the changes will take effect immediately.

Some key details to note:

  • This is only supported for Windows 10 / Windows Server Technical Preview guest operating systems at this point in time.
  • It is possible that, when you try to reduce the amount of memory assigned to a virtual machine, we will not be able to remove all the memory (due to it being accessed by the guest operating system).  If this happens – you will be notified that only some of the memory was removed – and the virtual machine settings will reflect the amount of memory now assigned to the virtual machine.