Windows 2000 Terminal Server performance degraded when running under ESXi 5.0

Symptoms

• Windows 2000 Terminal Server shows degraded performance when running under ESXi 5.0.
• Performance Charts for the virtual machine show a much higher CPU usage compared to the same virtual machine running on vSphere ESX/ESXi 4.x.
• Windows guest operating system task manager shows a very high CPU usage as soon as multiple Terminal Server users are connected.
• The guest operating system appears to intermittently become unresponsive due to the CPU load. A CPU spike for the System process may occur.
• Changing the virtual machine's hardware to version 8 or increasing the vCPU count does not resolve the issue.
• After migrating the virtual machine back to a host running ESX/ESXi 4.x, the virtual machine returns to normal behavior.

Cause

This behavior is caused by changes to the Binary Translation (BT) Monitor Mode of the VMware Hypervisor in version 5.0. These changes were included to address an issue related to coherency of translated code.

Resolution

This issue is resolved in ESXi 5.0 Update 1, for further information see the Resolved Issues section in the VMware ESXi 5.0 Update 1 Release Notes.


To workaround the issue on the previous versions of ESXi 5.0, perform one of these options:

• Migrate the virtual machine back to an ESX/ESXi 4.x host.
  
  This option is only possible if the virtual machine is still using Virtual Hardware Version 7 or lower. If the Virtual Hardware Version has already been upgraded to 8, you can use VMware Converter Standalone to downgrade the Hardware Version. For more information, see VMware vCenter Converter Standalone User's Guide.
• Manually change the Monitor Mode of the virtual machine from Binary Translation (BT) Monitor Mode ("Automatic" for Windows 2000 virtual machines) to use:
  • Intel VT-X/AMD-V for instruction set virtualization and software for MMU virtualization (HV)
    
    Or
  • Intel VT-X/AMD-V for instruction set virtualization and Intel EPT/AMD RVI for MMU virtualization (HWMMU)

The appropriate option depends on the features provided by your CPU.  To identify which features your CPU is capable of, check MONITOR MODE: allowed modes in the virtual machine's vmware.log (in the virtual machine folder on the datastore). For example:

2011-11-21T10:14:07.154Z| vmx| MONITOR MODE: allowed modes : BT HV HWMMU
2011-11-21T10:14:07.154Z| vmx| MONITOR MODE: user requested modes : BT HV HWMMU
2011-11-21T10:14:07.154Z| vmx| MONITOR MODE: guestOS preferred modes: BT HWMMU HV
2011-11-21T10:14:07.154Z| vmx| MONITOR MODE: filtered list : BT HWMMU HV
Where:

• allowed modes refers the mode your hardware is capable of
• user requested modes refers to the setting defined in the virtual machine configuration
• guestOS preferred modes refers to the default values for the selected guest operating system
• filtered list refers to the actual monitor mode used by the Hypervisor (in order of appearance)

reference
http://kb.vmware.com