In the release candidate build of service pack 1 for Windows Server 2008 R2 we have updated some parts of the Dynamic Memory user interface.
There were some top-level goals that we had with the Dynamic Memory user interface in the Hyper-V Manager (our MMC interface). Specifically we wanted users to be able to:
- Quickly see if their Hyper-V server was “in a good state”
- Quickly identify if specific virtual machines did not have enough memory
- Know how much memory was being used by each virtual machine
- Know how far away from “good” a given virtual machine was
To do this we used the current memory column and the memory availability column. Unfortunately, many users were confused by the memory availability column – specifically people were confused by what it meant to have a negative memory availability value. Rather than relying on the hope that every Hyper-V user in the world would read my blog – we decided to change what we displayed:
Specifically we have removed the memory availability column and replaced it with the memory demand and memory status columns (as well as renaming “current memory” to “Assigned Memory”). To understand what each of these columns display:
- Assigned Memory
- Like current memory in the beta release this simply displays how much memory is currently available to the virtual machine.
- Memory Demand
- This is a new value. This displays the amount of memory needed by the virtual machine at the moment – not including the requested memory buffer. So you can think of this as the minimum memory needed by the virtual machine. If you see the assigned memory go below the memory demand then the virtual machine is likely to be paging (this is equivalent to a negative memory availability).
- Memory Status
- This is a simple column that shows “OK”, “Low” or “Warning”. “OK” means that the virtual machine has at least 80% of its memory buffer. “Low” means that the virtual machine has more than the memory demand, but less than 80% of the memory buffer. “Warning” means that the virtual machine has less than the memory demand.