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Symptoms

Consider the following scenario:

  • You connect a storage device to a computer that is running Windows Server 2008 R2.

  • You configure Microsoft Multipath I/O (MPIO) and Microsoft Device Specific Module (MSDSM) as multiple paths that are configured to the storage array.

  • A path to the storage device fails and the path failover process starts.

In this scenario, the path failover process fails, and any application that tries to access the storage device may stop responding. Therefore, the MPIO path does not fail over.

Cause

This issue occurs because MPIO does not obtain the alternative path.

When MPIO tries to fail over to another path while another operation tries to remove the Logical Unit Number (LUN) for the failed path, either operation may occur first. However, MPIO does not obtain the alternative path if the LUN for the failed path is removed before MPIO accesses the device. Therefore, the failover operation fails.

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 Server 2008 R2 or Windows Server 2008 R2 Service Pack 1 (SP1).

For more information about how to obtain a 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, you do not have to change 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, 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
    0.20xxx

    Windows Server 2008 R2

    RTM

    LDR

    6.1.760
    1.21xxx

    Windows Server 2008 R2

    SP1

    LDR

  • The MANIFEST files (.manifest) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008 R2" section. 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

File name

File version

File size

Date

Time

Platform

Mpio.sys

6.1.7600.20921

156,544

11-Mar-2011

06:25

x64

Mpio.sys

6.1.7601.21680

156,544

11-Mar-2011

06:19

x64

Msdsm.sys

6.1.7600.20921

140,672

11-Mar-2011

06:25

x64

Msdsm.sys

6.1.7601.21680

140,672

11-Mar-2011

06:19

x64

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

File name

File version

File size

Date

Time

Platform

Mpio.sys

6.1.7600.20921

351,616

11-Mar-2011

05:21

IA-64

Mpio.sys

6.1.7601.21680

351,104

11-Mar-2011

05:16

IA-64

Msdsm.sys

6.1.7600.20921

348,032

11-Mar-2011

05:21

IA-64

Msdsm.sys

6.1.7601.21680

348,032

11-Mar-2011

05:16

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 MPIO, visit the following Microsoft TechNet website:

General information about MPIOFor 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 Server 2008 R2

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

File name

Amd64_mpio.inf_31bf3856ad364e35_6.1.7600.20921_none_79ee52ebc1f5caa0.manifest

File version

Not applicable

File size

2,073

Date (UTC)

11-Mar-2011

Time (UTC)

07:15

Platform

Not applicable

File name

Amd64_mpio.inf_31bf3856ad364e35_6.1.7601.21680_none_7b92ce39bf4dc7b4.manifest

File version

Not applicable

File size

2,073

Date (UTC)

11-Mar-2011

Time (UTC)

06:45

Platform

Not applicable

File name

Amd64_msdsm.inf_31bf3856ad364e35_6.1.7600.20921_none_2702b9050e2d1caf.manifest

File version

Not applicable

File size

2,079

Date (UTC)

11-Mar-2011

Time (UTC)

07:25

Platform

Not applicable

File name

Amd64_msdsm.inf_31bf3856ad364e35_6.1.7601.21680_none_28a734530b8519c3.manifest

File version

Not applicable

File size

2,079

Date (UTC)

11-Mar-2011

Time (UTC)

06:51

Platform

Not applicable

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

File name

Ia64_mpio.inf_31bf3856ad364e35_6.1.7600.20921_none_1dd15b5e09966266.manifest

File version

Not applicable

File size

2,071

Date (UTC)

11-Mar-2011

Time (UTC)

07:18

Platform

Not applicable

File name

Ia64_mpio.inf_31bf3856ad364e35_6.1.7601.21680_none_1f75d6ac06ee5f7a.manifest

File version

Not applicable

File size

2,071

Date (UTC)

11-Mar-2011

Time (UTC)

06:44

Platform

Not applicable

File name

Ia64_msdsm.inf_31bf3856ad364e35_6.1.7600.20921_none_cae5c17755cdb475.manifest

File version

Not applicable

File size

2,077

Date (UTC)

11-Mar-2011

Time (UTC)

07:22

Platform

Not applicable

File name

Ia64_msdsm.inf_31bf3856ad364e35_6.1.7601.21680_none_cc8a3cc55325b189.manifest

File version

Not applicable

File size

2,077

Date (UTC)

11-Mar-2011

Time (UTC)

06:49

Platform

Not applicable

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