Slow performance when an application retrieves a file on an SMB share by using the HTTP protocol in Windows 7 or in Windows Server 2008 R2

Symptoms

Assume that you have an application that uses the HTTP protocol on a computer that is running Windows 7 or Windows Server 2008 R2. The application retrieves a file that is larger than 64 kilobytes (KB) and that is stored on a Server Message Block (SMB) share. In this situation, you may experience slow file transfer performance.

Cause

This issue occurs because of the read logic that is implemented in the HTTP driver file (Http.sys). When an application retrieves a file that is larger than the Http.sys cache (64 KB), this error causes a redundant SMB read operation after a successful read operation.

Resolution

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 Web site:

http://support.microsoft.com/contactus/?ws=supportNote 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 7 Service Pack 1 (SP1) or 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:

976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2

Registry information

To use 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 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:

    Version

    Product

    Milestone

    Service branch

    6.1.760
    1.21xxx

    Windows 7 and 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 and for Windows 7" 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 x86-based versions of Windows 7

File name

File version

File size

Date

Time

Platform

Http.sys

6.1.7601.21805

514,048

31-Aug-2011

05:17

x86

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

File name

File version

File size

Date

Time

Platform

Http.sys

6.1.7601.21805

753,664

31-Aug-2011

05:20

x64

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

File name

File version

File size

Date

Time

Platform

Http.sys

6.1.7601.21805

1,442,816

31-Aug-2011

03:37

IA-64

Status

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

More Information

For more information about the Microsoft SMB protocol and the CIFS protocol, visit the following Microsoft website:

General information about the Microsoft SMB protocol and the CIFS protocolFor more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

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

File name

Update.mum

File version

Not Applicable

File size

1,643

Date (UTC)

31-Aug-2011

Time (UTC)

11:02

Platform

Not Applicable

File name

X86_3580540e3c1869d3d11f4e67446c7a1c_31bf3856ad364e35_6.1.7601.21805_none_e490dadbccf827c0.manifest

File version

Not Applicable

File size

692

Date (UTC)

31-Aug-2011

Time (UTC)

11:02

Platform

Not Applicable

File name

X86_microsoft-windows-http_31bf3856ad364e35_6.1.7601.21805_none_af5dd70190319da1.manifest

File version

Not Applicable

File size

175,661

Date (UTC)

31-Aug-2011

Time (UTC)

09:02

Platform

Not Applicable

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

File name

Amd64_0f61a2c454fc5d3fd11f6c459892da2f_31bf3856ad364e35_6.1.7601.21805_none_670859bdb2e530a6.manifest

File version

Not Applicable

File size

696

Date (UTC)

31-Aug-2011

Time (UTC)

11:02

Platform

Not Applicable

File name

Amd64_microsoft-windows-http_31bf3856ad364e35_6.1.7601.21805_none_0b7c7285488f0ed7.manifest

File version

Not Applicable

File size

175,667

Date (UTC)

31-Aug-2011

Time (UTC)

09:33

Platform

Not Applicable

File name

Update.mum

File version

Not Applicable

File size

1,853

Date (UTC)

31-Aug-2011

Time (UTC)

11:02

Platform

Not Applicable

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

File name

Ia64_7c35a3ed3acd4aa8fdcc32f787d21602_31bf3856ad364e35_6.1.7601.21805_none_1ebc04acdfa82704.manifest

File version

Not Applicable

File size

694

Date (UTC)

31-Aug-2011

Time (UTC)

11:02

Platform

Not Applicable

File name

Ia64_microsoft-windows-http_31bf3856ad364e35_6.1.7601.21805_none_af5f7af7902fa69d.manifest

File version

Not Applicable

File size

175,664

Date (UTC)

31-Aug-2011

Time (UTC)

09:19

Platform

Not Applicable

File name

Update.mum

File version

Not Applicable

File size

1,447

Date (UTC)

31-Aug-2011

Time (UTC)

11:02

Platform

Not Applicable

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