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Slim Down and Speed Up VMs with VM Optimizer

With this handy tool, your Windows VMs will be smaller and run faster than ever.

Many IT pros are faced with maintaining a virtual machine library or with having to package and take VMs on the road. One problem with maintaining a large amount of VMs on a computer’s hard disk or with copying VMs to removable media is the size requirements of virtual hard disks. A typical Windows Server 2003 basic installation in a VM, for example, consumes about 3GB of disk space.

If you have several VMs or environments consisting of multiple VMs, then optimizing the amount of storage space required by each VM is probably very important to you. If that’s that case, you should take a look at Invirtus VM Optimizer.

In my test lab, I recently used VM Optimizer to slim down the Windows Server 2003 VM that I use as a baseline image for each Microsoft Virtual Server VM that I manage. Before using VM Optimizer, the VM consumed 2.9 GB of storage space. After completing the optimization process, the VM’s virtual hard disk was reduced to a gig. I then zipped the optimized Windows 2003 VM and was able to reduce it to only 345 MB, which allows the VM to be copied to a CD-ROM, as well as consumes a lot less storage space on the server’s hard disk.

VM Optimizer supports several virtualization platforms, including Microsoft Virtual Server and Virtual PC, VMware Server, VMware Workstation and Virtual Iron, and can optimize Windows 2000 and newer guest operating systems.

VM Optimizer works by removing unneeded files and disabling unnecessary programs and services. Among the optimizations that are performed:

  • Stop and disable unnecessary services
  • Unistall MSN
  • Remove unnecessary files (temp, log, autorecover, help, service pack and Windows Update cache)
  • Defragment the virtual hard disk

While it’s true that you could manually do most of VM Optimizer’s changes on your own, its low price ($129 for the single user corporate edition) may have you asking yourself the question “Why would I want to?”

Using VM Optimizer is pretty straight forward. Basically, once you download the software and install it, you’ll have a CD-ROM ISO image file that contains the VM Optimizer program. To optimize a VM, you just need to mount the VM Optimizer ISO image file to the VM as a virtual CD-ROM drive, and with auto-run enabled in the VM’s guest OS, VM Optimizer will start once the CD is mounted.

VM Optimizer includes two unique CD-ISO builds: automated and manual. The automated version requires no user intervention. As soon as the VM Optimizer CD mounts to the virtual machine and auto-run launches VM Optimizer within the VM’s guest OS, the optimization process will automatically start and run to completion. With the manual version of VM Optimizer, you’ll have the ability to navigate through a wizard and select the specific optimizations that you would like performed.

Figure 1 shows available optimizations for a Windows 2003 guest OS. My preference is to use the manual optimization so that I can choose exactly what VM Optimizer removes or disables.

VM Optimizer options
[Click image to view larger version.]
Figure 1. Selecting the optimizations for VM Optimizer to perform

Once the optimization completes, you will need to click Finish in the VM Optimizer dialog box and the VM will automatically shut down. To recover the virtual hard disk space that was freed by VM Optimizer, you will need to perform an offline compaction of the virtual hard disk file. You can compact Virtual PC or Virtual Server vhd files by following these steps on the Invirtus Web site. VMware .vmdk virtual hard disk file compaction instructions are available here.

Note that you will not see a disk size reduction when compacting fixed-size or pre-allocated virtual hard disk files. In order to recover space from a fixed-size or pre-allocated virtual disk files, you first need to convert them into dynamically expanding virtual hard disks. Details on compacting fixed-size virtual hard disks are available in my Tech Line column, “Virtual Disk Compaction Confusion.”

If you have several Windows VMs that you need to shrink and optimize, then you should definitely take a look at Invirtus VM Optimizer. If your storage devices could clap, they would probably loudly applaud the purchase.

About the Author

Chris Wolf is VMware's CTO, Global Field and Industry.

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