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VMware Workstation 5.5

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Defragmentation of Disk Drives

Host disks, virtual disks and guest disks all affect the performance of VMware Workstation. See Defragmenting Virtual Disks for the procedures.

Host Hard Drives

Performance is weakened by fragmentation on the physical disk holding the virtual machine's working directory or virtual disk files. Fragmentation of the host disk can affect any or all of the following:

  • The files that hold a virtual disk
  • The files that store newly saved data when you have a snapshot
  • The files that hold information used in suspending and resuming a virtual machine

    • If you are experiencing slow disk performance in the virtual machine, or if you want to improve the speed of suspend and resume operations, check to be sure the host disk that holds the virtual machine's working directory and virtual disk files is not badly fragmented. If it is fragmented, you can improve performance by running a defragmentation utility to reduce fragmentation on that host disk.

    Virtual Drives

    Use the Workstation application to defragment virtual disks. See Defragmenting Virtual Disks.

    Guest Operating System Drives

    It is strongly recommended that you defragment using a guest operating system mechanism before taking the first snapshot (or linked clone).

  • Workstation makes all its changes to the redo log, not to the original disk, when you run a defragmenting program on the guest after a snapshot. You lose the ability to defragment inside the original disk forever.
  • Every sector that moves is copied to the redo log, making the virtual machine redo log extremely large when the disk is heavily fragmented and you run defragmentation after a snapshot.

    • Performance Impact of Defragmenting Snapshots and Linked Clones

    There may be a performance impact when you defragment a linked clone or a virtual machine with a snapshot. Exact performance degradation depends on:

  • The fragmentation of the parent virtual machine disk when you created the snapshot or linked clone.
  • The nature of the subsequent updates to the parent virtual machine disk.

    • Defragmentation tends to make the redo file grow. The redo file itself can become defragmented with respect to the host file system. If your use of virtual machines is strongly performance oriented, you should avoid defragmenting — or using — linked clones and snapshots.

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