Tuesday, March 07, 2006

To Virtualize or not to Virtualize...

… that is the question.

There has been a lot of discussion around the company about “Virtualizing”. This is where you take a production server, like your Print Server or Exchange Server, and run it on a shared system. I would just like to say now for the record, I do not believe in making your Exchange Server virtual. Yes, it is supported, but really a bad idea. Back to the topic at hand, there are two main applications that do this are Microsoft Virtual Server and VMWare Virtual Machine. There are two camps that feel that one is better than the other. I, personally, will run both. It does not matter to me which one is going to be used, that is up to the person writing the check. I do like VMWare over Virtual Server, even though VMWare is really bloody expensive. Microsoft did a nice job in making VS-R2, however, it does have some limitations. (and this is where I start the sh*t storm) VS is still in it infantancy stage. If you have a server with 100 processors, VS will only allocate you a single proc for that image, no matter if you are running server or not. VMWare, conversely, will allocate any or all resources that you have available. However, Microsoft is very easy to use and there is not all that fancy configuration that you have (can) do with VMWare. So, it comes down to…cost. (did you ever notice that most things come down to the all-mighty dollar) If you have a box that has beefy specs (and have money to spend), you probably would want to look at VMWare. However, if you want to go the inexpensive way and have a dual or quad box that you want to run WSUS in your production environment, Microsoft Virtual Server is the way to go.

There are some tips:

  1. Add more memory - Each virtual machine will require the same memory as a physical machine would. The more memory you have the more virtual machines you can run.
  2. Place the VHDs on a separate partition - For best performance the VHD files should be on a separate volume with a RAID array from the OS and other files.
  3. Like any Microsoft OS, the more fragmented the drive holding the data or VHDs the longer it will take to start, stop, pause and resume virtual machines. Defrag the OS drive, compact the VHDs and defrag the host systems drive where the VHDs are located on a regular basis. Virtual Server R2 includes Virtual Disk Precompactor for you to use before you compact a dynamically expanding VHD in order to create a smaller compacted VHD.
  4. Install VMAdditions - This is one of the most often overlooked issues with new virtual machines. The VMAdditions are special drivers used to improve performance on the virtual machines. Since, Virtual Server virtualizes standard hardware, the OS will install without the need for any drivers. Installing the VMAdditions will add functionality and increase performance of virtual machines.
  5. Use SCSI VHDs - All virtual machines should use SCSI VHDs. The SCSI driver will give the better performance over IDE VHDs no matter what type of hard drives the host system is using.
  6. Disable Real-time AV Scanning - Make sure you disable real-time virus scanning on the drive that contains the VHD files. You can also exclude the VHD and VMC files from real-time scanning.

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