A hotfix that lets you diagnose mini-filter-based performance issues in Windows Server 2008 R2 is available

This article introduces a new feature for Windows Server 2008 R2. After you install this hotfix, a logging mechanism is added to Filter Manager. This mechanism lets you diagnose mini-filter-based performance issues.

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 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 Windows Server 2008 R2 Service Pack 1 (SP1).

For more information about how to obtain a Windows 7 or Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:

Registry information

To apply the hotfix in this package, you do not have to make any changes to the registry.

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 Server 2008 R2 file information notes

Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

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

  Version	Product	SR_Level	Service branch
  6.1.760 1 . 21xxx	Windows Server 2008 R2	SP1	LDR

• 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" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain 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 x64-based versions 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: Currently, it is impossible to identify whether a mini-filter driver causes decreased performance on a computer.

In Windows Server 2003, Windows Server 2008, and Windows Server 2008 R2, the Fltmgr.sys driver in the file system stack enables file system filter drivers to be written as mini-filter drivers instead of full-filter drivers. This behavior prevents issues from occuring in operating systems that have lots of filter drivers. The Fltmgr.sys driver is an interface between the file system and the mini-filter drivers. Most operations are performed in the mini-filter driver. Because of the interface design, and because the Fltmgr.sys driver does not log events that can be read by current performance monitoring tools(for example, Xperf.exe), these tools cannot identify which mini-filters cause decreased performance. Therefore, the tools incorrectly determine that the performance decrease is caused by the Fltmgr.sys driver instead of the mini-filter driver. Therefore, you must remove or update suspect mini-filter drivers to troubleshoot this kind of issue.

After you apply the hotfix, you can find the name of a mini-filter that is causing performance problems on your computer. To obtain and display the data, download the latest Windows Assessment and Deployment Kit (ADK) and install the Windows Performance Toolkit. To download the Windows ADK, go to the following Microsoft website:

http://www.microsoft.com/download/en/details.aspx?id=28997

To run a trace, follow these steps:

1. Click Start, type command prompt in the Search box, and then click Command Prompt in the list of results.
2. At the command prompt, type the following command and then press Enter:
   • XPERF -on PROC_THREAD+LOADER+FLT_IO_INIT+FLT_IO+FLT_FASTIO+FLT_IO_FAILURE+FILENAME -stackwalk MiniFilterPreOpInit+MiniFilterPostOpInit
     
     Note This command starts a trace by using the memory as a buffer.
   • XPERF -start -f <traceFile>.etl -on PROC_THREAD+LOADER+FLT_IO_INIT+FLT_IO+FLT_FASTIO+FLT_IO_FAILURE+FILENAME -stackwalk MiniFilterPreOpInit+MiniFilterPostOpInit
     
     Note This command starts a trace by using <traceFile>.etl as a buffer to save memory. <traceFile>.etl is the file that is used as a backing store to store trace data, such as C:\temp\fltmgr.etl. You can add the +FILENAME switch if you want to log filenames of the files that the mini-filter is operating on.

To stop the trace and flush data to the trace file, type the following command and then press Enter:Note <mergedTrace>.etl is the final file which contains all trace information. <mergedTrace>.etl must be different from <traceFile>.etl.

For more information about the Xperf command, type xperf �help, and then press Enter.

To view the trace file, click <mergedTrace>.etl.

To view the mini-filter data, follow these steps:

1. Locate the Graph Explorer pane on the left side of Windows Performance Analyzer.
2. Expand the Storage node to show Mini-Filter Delays.
3. Right-click the Mini-Filter Delays area, then select Add to New Analysis View.

A tabular view of data is displayed. This data lists statistics, such as Mini-Filter Driver, Stack, Duration, Major Function Name, and File Name. You can use this data to determine mini-filter delays.

Additional file information

Additional file information for Windows Server 2008 R2

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

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