VMware Workstation 5.5

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General VMware Workstation Options

Guest Operating System Selection

Make certain you select the correct guest operating system for each of your virtual machines. To check the guest operating system setting, choose VM > Settings > Options > General.

VMware Workstation optimizes certain internal configurations on the basis of this selection. For this reason, it is important to set the guest operating system correctly. The optimizations can greatly aid the operating system they target, but they may cause significant performance degradation if there is a mismatch between the selection and the operating system actually running in the virtual machine. (Selecting the wrong guest operating system should not cause a virtual machine to run incorrectly, but it may degrade the virtual machine's performance.)

Memory Settings

Make sure to choose a reasonable amount of memory for your virtual machine. Many modern operating systems have a growing need for memory, so assigning a generous amount is a good thing.

The same holds true for the host operating system, especially a Windows host.

The New Virtual Machine Wizard automatically selects a reasonable starting point for the virtual machine's memory, but you may be able to improve performance by adjusting the settings in the virtual machine settings editor (VM > Settings > Memory).

If you plan to run one virtual machine at a time most of the time, a good starting point is to give the virtual machine half the memory available on the host.

Adjusting the application memory settings may also help. Go to Edit > Preferences > Memory.

For additional information, see Memory Usage Notes.

Debugging Mode

VMware Workstation can run in two modes — normal mode and a mode that provides extra debugging information. The debugging mode is slower than normal mode.

For normal use, check to be sure you are not running in debugging mode. Choose VM > Settings > Options and select Advanced. In the Advanced Options section, be sure there is no check in the Run with debugging information check box.

CD-ROM Drive Polling

Some operating systems — including Windows NT and Windows 98 — poll the CD-ROM drive every second or so to see whether a disc is present. (This allows them to run autorun programs.) This polling can cause VMware Workstation to connect to the host CD-ROM drive, which can make it spin up while the virtual machine appears to pause.

If you have a CD-ROM drive that takes especially long to spin up, there are two ways you can eliminate these pauses.

  • You can disable the polling inside your guest operating system. The method varies by operating system. For recent Microsoft Windows operating systems, the easiest way is to use TweakUI from the PowerToys utilities.
  • For information on finding TweakUI and installing it in your guest operating system, go to www.microsoft.com and search for TweakUI. Specific instructions depend on your operating system.

  • Another approach is to configure your virtual CD-ROM drive to start disconnected. The drive appears in the virtual machine, but it always appears to contain no disc (and VMware Workstation does not connect to your host CD-ROM drive).
  • To make this change, choose VM > Settings. Click the DVD/CD-ROM item in the Device list. Then clear the Connect at Power On check box.

    When you want to use a CD-ROM in the virtual machine, choose VM > Removable Devices menu and connect the CD-ROM drive.

    Disk Options

    The various disk options (SCSI versus IDE) and types (virtual or physical) affect performance in a number of ways.

    Inside a virtual machine, SCSI disks and IDE disks that use direct memory access (DMA) have approximately the same performance. However, IDE disks can be very slow in a guest operating system that either cannot use or is not set to use DMA.

    The easiest way to configure a Linux guest to use DMA for IDE drive access is to install VMware Tools (VM > Install VMware Tools). Among other things, the installation process automatically sets IDE virtual drives to use DMA.

    In Windows 2000, DMA access is enabled by default. In other Windows guest operating systems, the method for changing the setting varies with the operating system. See the following technical notes for details.

    When a snapshot exists, virtual disks often have very good performance for random or nonsequential access. But they can potentially become so fragmented that performance is affected. In order to defragment the disk, you must first delete the snapshot (VM > Snapshot > Snapshot Manager > Delete).

    When no snapshot exists, physical disks and virtual disks with all the space allocated in advance both use flat files that mimic the sequential and random access performance of the underlying disk. When a snapshot exists and you have made changes since powering on the virtual machine, any access to those changed files performs at a level similar to the performance of a virtual disk that does not have all space allocated in advance. If you delete the snapshot, performance is again similar to that of the underlying disk.

    Overall, if no snapshot exists and you are using physical disks or virtual disks with all the space allocated in advance, you see somewhat better performance than that provided by other configurations.

    Disk writes may be slower for virtual disks that do not have all space allocated in advance. However, you can improve performance for these disks by defragmenting them from the virtual machine settings editor. Choose VM > Settings, select the disk you want to defragment, then click Defragment.

    Remote Disk Access

    Whenever possible, do not use disks that are on remote machines and accessed over the network unless you have a very fast network. If you must run disks remotely, choose VM > Settings > Options, select General and set the Working directory to a directory on your local hard disk. Then take a snapshot. After you take the snapshot, changes you make are stored locally in the working directory.


    If you do not need to use the snapshot feature, it is best to run your virtual machine with no snapshot. This provides best performance. To be sure a virtual machine has no snapshot, choose VM > Snapshot > Snapshot Manager. If you see a snapshot you do not want, select it and click the Delete button.


    See Defragmentation of Disk Drives for information about keeping disk drives efficient.

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