Some ways you can improve performance include:
Make certain you select the correct guest operating system for each of your virtual machines. To check the guest operating system setting, choose Settings > Configuration Editor > Misc.
VMware GSX Server optimizes certain internal configurations on the basis of this selection. For this reason, it is important to set the guest operating 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.)
Make sure to choose a reasonable amount of memory for your virtual machine. Many modern operating systems are increasingly hungry for memory, so assigning a healthy amount is a good thing.
The same holds true of the host operating system, especially a Windows host operating system.
The Configuration 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 Configuration Editor (Settings > Configuration Editor > 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 host reserved memory settings may also help: Settings > Reserved Memory.
VMware GSX Server 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 aren't running in debugging mode.
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 GSX Server 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.
Disable the polling inside your guest operating system. This 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.
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 GSX Server does not connect to your host CD-ROM drive).
To make this change, go to Settings > Configuration Editor. Expand either IDE Drives or SCSI Devices (depending on how you have configured your virtual CD-ROM drive) and click the device that represents your virtual CD-ROM drive. Then deselect the Start Connected option.
When you want to use a CD-ROM in the virtual machine, go to the Devices menu and connect the CD-ROM drive.
The various disk options (SCSI versus IDE) and types (virtual or raw) 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 operating system to use DMA for IDE drive access is to install VMware Tools (Settings > VMware Tools Install). Among other things, the installation process automatically sets IDE virtual drives to use DMA.
In Windows 2000 guest operating systems, DMA access is enabled by default. In other Windows guest operating systems, the method for changing the setting varies with the operating system.
Virtual disks in nonpersistent and undoable mode often have very good performance for random or nonsequential access. But they can potentially become fragmented (at a level that cannot be fixed with defragmentation tools inside the guest). This can slow performance.
When run in persistent mode, raw disks (and plain disks, which may have been created under VMware GSX Server 1.0) both use flat files that mimic the sequential and random access performance of the underlying disk. When you are using undoable mode and 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. Once you commit the changes, performance is again similar to that of the underlying disk.
Overall, if you are using raw (or plain) disks in persistent mode, you should see somewhat better performance than that provided by other disk types and modes.
In exchange, because you are using persistent mode, you sacrifice the option of undoability. And because you are not using virtual disks, you cannot take advantage of the fact that virtual disks initially have a small footprint in the host file system and grow only as needed when you fill the virtual disk.
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, make certain to use undoable disks, then go to Settings > Configuration Editor > Misc and set the REDO log directory field to a directory on your local hard disk.
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