The LUN for a storage device is lost when multiple paths are lost concurrently in Windows

Symptoms

Assume that you configure a Windows Server 2012 R2, Windows Server 2012 or Windows Server 2008 R2-based computer to use Microsoft Multipath I/O (MPIO) and Microsoft Device Specific Module (DSM). You connect a storage device to the computer by using redundant physical paths. In this scenario, when multiple paths are lost concurrently, the logical unit number (LUN) for the storage device is lost on the computer.

Cause

This problem occurs because, while the system tries to fail over one of the paths to the other path, the other path has also failed.

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 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, you must be running one of the following operating systems:

  • Windows Server 2012 R2

  • Windows Server 2012

  • Windows Server 2008 R2

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any previously released hotfix.

The English (United States) 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 2012 R2 file information notes

Important Windows 8.1 and Windows Server 2012 R2 hotfixes are included in the same packages. However, only "Windows 8.1" 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 8.1" 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

    6.3.960 0.16 xxx

    Windows Server 2012 R2

    RTM

    GDR

  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information" section. MUM, MANIFEST, 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 2012 R2

File name

File version

File size

Date

Time

Platform

Mpio.sys

6.3.9600.16523

239,448

31-Jan-2014

16:17

x64

Windows Server 2012 file information and notes

Important Windows 8 and Windows Server 2012 hotfixes are included in the same packages. However, only "Windows 8" 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 8" 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

    6.2.920 0.20 xxx

    Windows Server 2012

    RTM

    LDR

  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information" 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 2012

File name

File version

File size

Date

Time

Platform

Mpio.sys

6.2.9200.20848

237,912

12-Oct-2013

09:05

x64

Windows Server 2008 R2 file information and 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
    1.22xxx

    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) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are critical 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 x64-based versions of Windows Server 2008 R2

File name

File version

File size

Date

Time

Platform

Mpio.inf_loc

Not applicable

1,290

03-Dec-2013

09:50

Not applicable

Mpio.inf_loc

Not applicable

1,270

03-Dec-2013

09:52

Not applicable

Mpio.inf_loc

Not applicable

1,266

03-Dec-2013

09:50

Not applicable

Mpio.inf_loc

Not applicable

1,256

03-Dec-2013

09:52

Not applicable

Mpio.inf_loc

Not applicable

1,316

03-Dec-2013

09:49

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

08:42

Not applicable

Mpio.inf_loc

Not applicable

1,296

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

09:49

Not applicable

Mpio.inf_loc

Not applicable

1,298

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,282

03-Dec-2013

09:49

Not applicable

Mpio.inf_loc

Not applicable

1,278

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

09:52

Not applicable

Mpio.inf_loc

Not applicable

1,242

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

09:49

Not applicable

Mpio.inf_loc

Not applicable

1,280

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,300

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,306

03-Dec-2013

09:52

Not applicable

Mpio.inf_loc

Not applicable

1,292

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,260

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,272

03-Dec-2013

09:52

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

09:53

Not applicable

Mpio.inf_loc

Not applicable

1,238

03-Dec-2013

09:53

Not applicable

Mpio.sys

6.1.7601.22529

160,704

03-Dec-2013

08:48

x64

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

File name

File version

File size

Date

Time

Platform

Mpio.inf_loc

Not applicable

1,256

03-Dec-2013

09:30

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

07:52

Not applicable

Mpio.inf_loc

Not applicable

1,298

03-Dec-2013

09:30

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

09:27

Not applicable

Mpio.inf_loc

Not applicable

1,242

03-Dec-2013

09:31

Not applicable

Mpio.inf_loc

Not applicable

1,258

03-Dec-2013

09:25

Not applicable

Mpio.inf_loc

Not applicable

1,238

03-Dec-2013

09:31

Not applicable

Mpio.sys

6.1.7601.22529

366,528

03-Dec-2013

07:56

IA-64


Status

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

References

See the terminology Microsoft uses to describe software updates.

Additional file information

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