Improving Virtual Machine Performance

There is some overhead in running a guest operating in a virtual machine, but the system should still be usable. (Note that there is additional overhead in beta distributions because the software is compiled to aid debugging and is not fully optimized for speed.) For optimal performance, make sure you are using the latest released version. If your virtual machine is too slow to be usable, check the following, but also see www.vmware.com/support/gsx25/doc/performance_gsx.html (for GSX Server 2.5) or www.vmware.com/support/gsx2/doc/performance_gsx.html (for GSX Server 2.0.x).

• Did you install VMware Tools in the guest operating system?

  If you did not, do so now. The VMware Tools package includes a display driver that has been optimized for the guest operating system running within a virtual machine. If this optimized driver is not installed, the guest operating system falls back to using a standard VGA device driver that is completely emulated in software and display performance suffers dramatically.

  VMware Tools packages for Windows, Linux, FreeBSD, and NetWare guests are included with VMware GSX Server.

  If VMware Tools is not installed on the guest operating system, check www.vmware.com/support/gsx25/doc/tools_install_gsx.html (for GSX Server 2.5) or www.vmware.com/support/gsx2/doc/tools_install_gsx.html (for GSX Server 2.0.x) for instructions on installing the package in your guest operating system.

• Are you running the latest version of VMware Tools in the guest operating system?

  If you are not, you should upgrade to the latest version. The VMware Tools package for GSX Server 2.5 virtual machines also includes improved networking and SCSI drivers. To install the latest version of VMware Tools, go to:
  www.vmware.com/support/gsx25/doc/tools_install_gsx.html.

• Did you assign too much memory to the virtual machine and leave none for the host?

  It is possible that the host operating system doesn't have enough memory to operate efficiently, if you increased the amount of memory reserved to run virtual machines above the recommended setting. On Windows hosts, choose Settings > Preferences > Memory to see these settings. On Linux hosts, choose Settings > Reserved Memory.

  If free memory falls below the minimum necessary value (specific to each host computer's configuration), the host operating system continually frees up memory by swapping to disk to maintain that amount of free memory. This swapping causes the virtual machine to run slowly as well. When reserving memory for a virtual machine, you must leave enough memory for the host operating system to operate efficiently.

• Did you assign too little memory to the virtual machine?

  Make sure the virtual machine is configured with enough memory that matches the operating system vendor's requirements. To change the memory setting for a virtual machine on a Windows host, choose Settings > Configuration Editor, then select Memory on the Hardware tab to see these settings. On a Linux host, choose Settings > Configuration Editor > Memory.

• Are you running the local console in full screen mode or in a window?

  You get the best display performance when the virtual machine takes over the full screen. To switch to full screen mode, click Full Screen on the local console toolbar.

• Are you using DMA for access to IDE drives on host and guest?
  
  
  For details on making these settings, see www.vmware.com/support/gsx25/doc/performance_gos-9x_gsx.html (for GSX Server 2.5) or www.vmware.com/support/gsx2/doc/performance_gos-9x_gsx.html (for GSX Server 2.0.x).
  
  
• Is the host unresponsive or hard to interact with while a virtual machine is busy?
  
  
  On a Windows host, you might be able to get better responsiveness from the host by decreasing the scheduler priority level of the running virtual machines. To lower the priority level, choose Settings > Local Priority.
  
  
• Is the virtual machine unresponsive or hard to interact with while the host is busy?
  
  
  You might be able to get better responsiveness from the virtual machine by releasing the mouse from the virtual machine (Ctrl-Alt) and increasing the virtual machine's priority level. To raise the priority level, choose Settings > Local Priority.
  
  
• Does the virtual machine intermittently halt or become unresponsive?

  If you are not getting a significant fraction of the host processor, check the following:

  • Your host might have CD-ROM autoplay enabled. You should disable that function.
  • Your host system configuration might be underpowered. For example, you might not have enough memory to run all the applications and virtual machines you want to run concurrently.
  • Your virtual machine's disk files and any associated files such as redo logs might be mounted on a networked file system. Try running your virtual machine with all the data files stored on local file systems and with no other CPU-consuming applications running. You can also reduce the memory size for your virtual machines, or add more physical memory to the host machine.
    
    
• Is there a virtual machine running DOS or some other operating system that idles poorly?

  See the DOS idle notes in the installation notes for DOS and Windows 3.1 guest operating systems. Go to www.vmware.com/support/gsx25/doc/guestos_win31dos_gsx.html (for GSX Server 2.5) or www.vmware.com/support/gsx2/doc/guestos_win31dos_gsx.html (for GSX Server 2.0.x).

  For NetWare guest operating systems running under GSX Server 2.5, the CPU idler program is included with VMware Tools. Make sure you upgrade VMware Tools to the version included with GSX Server 2.5. See www.vmware.com/support/gsx25/doc/tools_install_netware_gsx.html.

  For NetWare guest operating systems running under GSX Server 2.0.x, see the installation notes for the specific NetWare version installed in the virtual machine for information on the idler program. See www.vmware.com/support/gsx2/doc/guestos_netware_gsx.html.

• Is an ActiveX desktop used inside a virtual machine running Windows 95 or Windows 98?
  
  
• Are you using animated effects in a Windows guest operating system?

  To increase responsiveness from your Windows guest operating system, disable animated windows, menus, and lists by deselcting the option from the Effects tab of the Display Properties dialog box.

• Are you using an unsupported guest operating system?

  Check the list of supported and unsupported guest operating systems at www.vmware.com/support/gsx25/doc/guestos_supported_gsx.html (for GSX Server 2.5) or www.vmware.com/support/gsx2/doc/guestos_supported_gsx.html (for GSX Server 2.0.x).

  Unsupported operating systems can run slowly, if they run at all.

• Are your virtual machines using host-only or NAT networking and on a Windows host?

  Networking performance on your host may slow down when browsing your Windows host and network. VMware GSX Server's virtual networking installs two virtual Ethernet interfaces on the host so that your host can access the host-only and NAT virtual networks, which in turn allow your host to access the virtual machines running on those networks and allow those virtual machines to access the host. If you are already connected to a network, you might notice that it takes a little longer to find all the machines on your physical network because the host checks the virtual networks for any virtual machines that are running.

  If your virtual machines are not using NAT or host-only networking or are not running at the moment, you can disable the virtual network adapters to improve your host's networking and browsing capabilities.

  Disabling the Virtual Network Interfaces on a Windows Server 2003 Host

  1. Open the Control Panel and double-click Network and Dial-up Settings.
  2. Right-click the host-only adapter and choose Properties.
  3. Click Configure.
  4. In the Device Usage list, select Disable from this HW profile.
  5. Repeat these steps for the NAT adapter.
  6. Click OK twice to exit the dialog boxes.

  Disabling the Virtual Network Interfaces on a Windows 2000 Host

  1. Open the Control Panel and double-click Network and Dial-up settings.
  2. Right-click the host-only adapter and choose Disable.
  3. Right-click the NAT adapter and choose Disable.

  Disabling the Virtual Network Interfaces on a Windows NT Host

  1. Open the Control Panel and double-click Network.
  2. Click the Bindings tab.
  3. Click All adapters.
  4. Check the host-only and NAT adapters, then click Disable.
  5. Click OK to exit.
     
     
• Is this a virtual machine with a Windows Server 2003, Windows XP or Windows 2000 guest operating system?

  If so, you can use a different network driver to improve network performance.

  For information on switching the driver for GSX Server 2.5, go to www.vmware.com/support/gsx25/doc/network_adv_vmxnet_gsx.html.

  For information on switching the driver for GSX Server 2.0.x, see www.vmware.com/support/kb/enduser/std_adp.php?p_faqid=762.