Symptoms

Consider the following scenario:

  • You have a computer that is running Windows Server 2008 or Windows Server 2008 R2.

  • You connect the computer to a storage device that is controlled by Microsoft Multipath I/O (MPIO).

  • A transient path failure occurs. For example, a non-perfect SAN fabric that has an occasional frame drops, or a switch port experiences an outage in a short time.

In this scenario, an MPIO path failover occurs incorrectly. The expected behavior is that the Mpio.sys driver can handle the transient device errors and does not trigger the MPIO path failover operation.

Cause

The issue occurs because the mpio.sys driver incorrectly identifies an intermittent path failure as a device failure. Therefore, a MPIO total path failover operation is triggered incorrectly.

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 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 exist, 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:

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, your computer must be running one of the following operating systems:

  • Windows Server 2008

  • Windows Server 2008 with Service Pack 2 (SP2)

  • Windows Server 2008 R2

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

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

968849 How to obtain the latest service pack for Windows Server 2008For 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 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 file information notes

Important Windows Vista hotfixes and Windows Server 2008 hotfixes are included in the same packages. However, only "Windows Vista" is listed on the Hotfix Request page. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows Vista" 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

    6.0.600 1. 22xxx

    Windows Server 2008

    SP1

    LDR

    6.0.600 2. 22xxx

    Windows Server 2008

    SP2

    LDR

  • Service Pack 1 is integrated into the release version of Windows Server 2008. Therefore, RTM milestone files apply only to Windows Vista. RTM milestone files have a 6.0.0000.xxxxxx version number.

  • 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 and for Windows Vista" section. MUM files and MANIFEST files, and the associated security catalog (.cat) files, are very important to maintaining the state of the updated component. 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 Server 2008

File name

File version

File size

Date

Time

Platform

Mpio.sys

6.0.6001.22914

106,384

06-May-2011

20:02

x86

Mpio.sys

6.0.6002.22637

106,896

06-May-2011

20:02

x86

For all supported x64-based versions of Windows Server 2008

File name

File version

File size

Date

Time

Platform

Mpio.sys

6.0.6001.22914

130,448

06-May-2011

19:58

x64

Mpio.sys

6.0.6002.22637

130,960

06-May-2011

19:58

x64

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

File name

File version

File size

Date

Time

Platform

Mpio.sys

6.0.6001.22914

291,216

06-May-2011

19:55

IA-64

Mpio.sys

6.0.6002.22637

292,240

06-May-2011

19:55

IA-64

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 0.16xxx

    Windows Server 2008 R2

    RTM

    GDR

    6.1.760 0.20xxx

    Windows Server 2008 R2

    RTM

    LDR

    6.1.760 1.17xxx

    Windows Server 2008 R2

    SP1

    GDR

    6.1.760 1.21xxx

    Windows Server 2008 R2

    SP1

    LDR

  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.

  • The MANIFEST files (.manifest) that are installed for each environment are listed separately in the "Additional file information for Windows 7" section. MANIFEST files and the associated security catalog (.cat) files, are very important 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 x64-based versions of Windows 7 and of Windows Server 2008 R2

File name

File version

File size

Date

Time

Platform

Mpio.sys

6.1.7600.16818

156,544

20-May-2011

12:50

x64

Mpio.sys

6.1.7600.20970

157,568

20-May-2011

12:53

x64

Mpio.sys

6.1.7601.17619

156,544

20-May-2011

12:49

x64

Mpio.sys

6.1.7601.21731

157,568

20-May-2011

15:35

x64

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

File name

File version

File size

Date

Time

Platform

Mpio.sys

6.1.7600.16818

350,080

20-May-2011

11:52

IA-64

Mpio.sys

6.1.7600.20970

355,712

20-May-2011

11:47

IA-64

Mpio.sys

6.1.7601.17619

350,080

20-May-2011

11:54

IA-64

Mpio.sys

6.1.7601.21731

355,712

20-May-2011

15:17

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 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

Additional files for all supported x86-based versions of Windows Server 2008

File name

Update.mum

File version

Not applicable

File size

3,078

Date (UTC)

06-May-2011

Time (UTC)

20:10

Platform

Not applicable

File name

X86_mpio.inf_31bf3856ad364e35_6.0.6001.22914_none_1db5b9d2a87649bd.manifest

File version

Not applicable

File size

1,659

Date (UTC)

06-May-2011

Time (UTC)

20:10

Platform

Not applicable

File name

X86_mpio.inf_31bf3856ad364e35_6.0.6002.22637_none_1f898cc0a5aa22c8.manifest

File version

Not applicable

File size

1,659

Date (UTC)

06-May-2011

Time (UTC)

20:10

Platform

Not applicable

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

File name

Amd64_mpio.inf_31bf3856ad364e35_6.0.6001.22914_none_79d4555660d3baf3.manifest

File version

Not applicable

File size

1,661

Date (UTC)

06-May-2011

Time (UTC)

20:10

Platform

Not applicable

File name

Amd64_mpio.inf_31bf3856ad364e35_6.0.6002.22637_none_7ba828445e0793fe.manifest

File version

Not applicable

File size

1,661

Date (UTC)

06-May-2011

Time (UTC)

20:10

Platform

Not applicable

File name

Update.mum

File version

Not applicable

File size

3,102

Date (UTC)

06-May-2011

Time (UTC)

20:10

Platform

Not applicable

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

File name

Ia64_mpio.inf_31bf3856ad364e35_6.0.6001.22914_none_1db75dc8a87452b9.manifest

File version

Not applicable

File size

1,660

Date (UTC)

06-May-2011

Time (UTC)

20:10

Platform

Not applicable

File name

Ia64_mpio.inf_31bf3856ad364e35_6.0.6002.22637_none_1f8b30b6a5a82bc4.manifest

File version

Not applicable

File size

1,660

Date (UTC)

06-May-2011

Time (UTC)

20:10

Platform

Not applicable

File name

Update.mum

File version

Not applicable

File size

2,257

Date (UTC)

06-May-2011

Time (UTC)

20:09

Platform

Not applicable

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_6.1.7600.16818_none_79768812a8c9c046.manifest

File version

Not applicable

File size

2,073

Date (UTC)

20-May-2011

Time (UTC)

19:04

Platform

Not applicable

File name

Amd64_mpio.inf_31bf3856ad364e35_6.1.7600.20970_none_79b74305c21f3cfe.manifest

File version

Not applicable

File size

2,073

Date (UTC)

20-May-2011

Time (UTC)

19:08

Platform

Not applicable

File name

Amd64_mpio.inf_31bf3856ad364e35_6.1.7601.17619_none_7b5de562a5ef4589.manifest

File version

Not applicable

File size

2,073

Date (UTC)

20-May-2011

Time (UTC)

19:10

Platform

Not applicable

File name

Amd64_mpio.inf_31bf3856ad364e35_6.1.7601.21731_none_7bc9e005bf24527d.manifest

File version

Not applicable

File size

2,073

Date (UTC)

20-May-2011

Time (UTC)

20:35

Platform

Not applicable

File name

Update-bf.mum

File version

Not applicable

File size

3,108

Date (UTC)

21-May-2011

Time (UTC)

00:10

Platform

Not applicable

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

File name

Ia64_mpio.inf_31bf3856ad364e35_6.1.7600.16818_none_1d599084f06a580c.manifest

File version

Not applicable

File size

2,071

Date (UTC)

20-May-2011

Time (UTC)

19:03

Platform

Not applicable

File name

Ia64_mpio.inf_31bf3856ad364e35_6.1.7600.20970_none_1d9a4b7809bfd4c4.manifest

File version

Not applicable

File size

2,071

Date (UTC)

20-May-2011

Time (UTC)

19:06

Platform

Not applicable

File name

Ia64_mpio.inf_31bf3856ad364e35_6.1.7601.17619_none_1f40edd4ed8fdd4f.manifest

File version

Not applicable

File size

2,071

Date (UTC)

20-May-2011

Time (UTC)

19:08

Platform

Not applicable

File name

Ia64_mpio.inf_31bf3856ad364e35_6.1.7601.21731_none_1face87806c4ea43.manifest

File version

Not applicable

File size

2,071

Date (UTC)

20-May-2011

Time (UTC)

20:34

Platform

Not applicable

File name

Update-bf.mum

File version

Not applicable

File size

1,895

Date (UTC)

21-May-2011

Time (UTC)

00:09

Platform

Not applicable

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