The RegQueryValueEx function returns a very large incorrect value for the "Avg. Disk sec/Transfer" performance counter in Windows Server 2008 R2 or in Windows 7

Consider the following scenario:

• You have a computer that is running Windows Server 2008 R2 or Windows 7.
• You query for the value of the "Avg. Disk sec/Transfer" performance counter by using the RegQueryValueEx function.

In this scenario, a very large, incorrect value is returned by the function.

Note

• This issue does not occur if you collect the value of the same performance counter by using the performance monitor utility.
• This issue may occur if any application or any service uses the sample code that is described in the following MSDN article:
  
  Retrieving Counter Data (http://msdn.microsoft.com/library/aa373178(v=VS.85).aspx)
  For example, you use System Center Operations Manager 2007 to monitor the health status of a Windows Server 2008 R2-based computer. You may receive wrong alerts for troubleshooting because of this issue.

This behavior occurs because of an issue in the volume manager driver (Volmgr.sys).

Some applications or services close the handle to HKEY_PERFORMANCE_DATA every time that the RegQueryValueEx function is called. Then, the disk counter is enabled or disabled intermittently by the kernel provider, and time stamps of some I/O request packets (IRPs) are not recorded when the disk counter is disabled. Therefore, not-valid data that does not have a time stamp is calculated and returned by the function.

Note In Windows Server 2008 R2 and in Windows 7, the disk counter in kernel provider can be dynamically enabled or disabled. If the handle to HKEY_PERFORMANCE_DATA is closed, the kernel provider disables I/O performance trace.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem that is described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix, you must be running one of the following operating systems:

• Windows 7
• Windows 7 with Service Pack 1 (SP1)
• Windows Server 2008 R2
• Windows Server 2008 R2 with Service Pack 1 (SP1)

Registry information

You do not have to make any changes to the registry to use this hotfix.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows 7 and Windows Server 2008 R2 file information notes

• The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
  Collapse this tableExpand this table

  Version	Product	Milestone	Service branch
  6.1.760 0.20xxx	Windows 7 and Windows Server 2008 R2	RTM	LDR
  6.1.760 1.17xxx	Windows 7 and Windows Server 2008 R2	SP1	GDR
  6.1.760 1.21xxx	Windows 7 and Windows Server 2008 R2	SP1	LDR

• GDR service branches contain only those fixes that are widely released to address widespread, very important issues. LDR service branches contain hotfixes in addition to widely released fixes.
• The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008 R2 and for Windows 7" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are critical to maintaining the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

For all supported x86-based versions of Windows 7

For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

For all supported IA-64-based versions of Windows Server 2008 R2

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: For more information about RegQueryValueEx function, visit the following Microsoft webpage:

Additional file information

Additional file information for Windows 7 and for Windows Server 2008 R2

Additional files for all supported x86-based versions of Windows 7

Additional files for all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

Additional files for all supported IA-64-based versions of Windows Server 2008 R2