Wednesday, 18 April 2007

Virtual Server - VSS Service and Virtual Machine Memory Usage

We utilize Microsoft Virtual Server 2005 R2 on a number of different hardware platforms running a number of different operating systems.

One of the curious things that I have noticed is with regards to memory management by the VSS service.

The following is a screen shot of the server's Task Manager Process Tab:

The VSS service is using about 12 MB of physical memory.

The configuration of this particular machine is as follows:
  • Intel SR2300 2U
  • Two Intel Xeon 2.8 GHz CPUs
  • 6 GB ECC PC2700 RAM
  • Dual Seagate 76 GB SCA2 SCSI SW RAID 1
  • Windows Server 2003 Enterprise with PAE switch
We have loaded up two XP Pro SP2 and two Vista Business virtual machines with both having an allotted 1 GB of system memory.

The above Task Manager shot was taken while all four virtual machines were running. There is no evidence from the service memory usage that they are running.

However, on the Performance Tab, we see the following:

The server has a total of 4.21 GB of RAM allotted to running processes.

So, somewhere in there, the VSS has grabbed the necessary physical RAM and made sure that the respective machines are getting what they need.

To date, other than one glitch with one of the Virtual Vista machines blue screening on a boot up, we have had trouble free performance.

The primary purpose for this platform is to test virtualizing the desktop OS environment to provide our clients with a solid alternative to Terminal Services.

The Microsoft Virtual Server 2005 R2 site.

Philip Elder
Microsoft Small Business Specialists

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