XenApp Servers Return a Full Load when Advanced or Custom Load Evaluators are Assigned

XenApp Servers Return a Full Load when Advanced or Custom Load Evaluators are Assigned

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Article ID: CTX115686

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Updated On:

Description

Citrix XenApp servers return a full load when Advanced or Custom Load Evaluators are assigned.

Environment

Caution! Using Registry Editor incorrectly can cause serious problems that might require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. Be sure to back up the registry before you edit it.

Resolution

Check that the Windows Performance Library (Perflib) service or any relevant performance sub key has not been disabled. This can be checked by completing the following procedure: 

Caution! Refer to the Disclaimer at the end of this article before using Registry Editor.

  1. Navigate to the following registry keys:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Perflib
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PerfDisk\Performance
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PerfProc\Performance
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PerfOS\Performance

  2. Confirm that the following value does not exist: disable performance counters = 1

  3. If the preceding value exists, change the value data to 0 or delete the value completely.
    Note: The preceding actions do not require restarting the server.

  1. Ensure that the Network Service account has Read permissions to the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Perflib key.

  2. If you have several XenApp servers in the farm exhibiting this issue, complete the following procedure to fix the issue:

    1. Create a group policy that grants Performance Log User and Performance Monitor Users with Read permissions to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\PerfLib.

    2. Allow the computer policy to update on the XenApp servers.

    3. Restart the IMA Service.

Problem Cause

The Perflib service has been disabled. The following registry setting is configured:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Perflib
Value Name: disable performance counters
Value Type: DWORD
Value: 1

Or

A relevant performance sub key has been disabled, such as PerfDisk, PerfProc, or PerfOS. 
The following example registry setting disables PerfDisk:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\PerfDisk\Performance
Value Name: disable performance counters
Value Type: DWORD
Value: 1

Issue/Introduction

This article provides information on Citrix XenApp servers returning a full load when Advanced or Custom Load Evaluators are assigned.

Additional Information

Perflib is responsible for retrieving registry-based performance counters on the system. If the following registry value is set to 1, Perflib does not retrieve performance counter data from the registry. As a result, the System Monitor and other tools that use the data cannot display it. Instead, when a program requests performance data from the registry, the system returns an error to the program explaining that the Perflib service is disabled.
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Perflib
Value Name: disable performance counters
Value Type: DWORD
Value: 1

0 = Enables performance counters. Programs can retrieve performance data from the registry.
1 = Disables performance counters. Programs cannot retrieve performance data from the registry.

Perflib is also responsible for detecting disabling errors in the performance sub-keys referenced in this article. It disables the counters by setting the value of the Disable Performance Counters entry to 1. 

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