Consider the following scenario:
- You configure a Windows Server 2008 R2-based or Windows Server 2012-based computer to use Microsoft Multipath I/O (MPIO) and Microsoft Device Specific Module (MDSM).
- You connect a storage device to the computer. The storage device is configured to use Asymmetric Logical Unit Access (ALUA).
- A path failover occurs between storage controllers.
This issue occurs because of a race condition that occurs in the Msdsm.sys file.
Update information for Windows Server 2012To resolve this issue in Windows Server 2012, install update rollup 2889784. For more information about how to obtain this update rollup package, click the following article number to view the article in the Microsoft Knowledge Base:
2889784 Windows RT, Windows 8, and Windows Server 2012 update rollup: November 2013
Hotfix information for Windows Server 2008 R2To resolve this issue in Windows Server 2008 R2, install the hotfix that is described in this article.
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.
PrerequisitesTo 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:
976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2
Registry informationTo apply this hotfix, you do not have to make any changes to the registry.
Restart requirementYou must restart the computer after you apply this hotfix.
Hotfix replacement informationThis hotfix does not replace a previously released hotfix.
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:
824684 Description of the standard terminology that is used to describe Microsoft software updates