I/O failure during MPIO path failover in Windows Server 2008 R2 SP1


Consider the following scenario:
  • You configure a computer that is running Windows Server 2008 R2 Service Pack 1 (SP1) to use Microsoft Multipath I/O (MPIO).
  • You connect a storage device that is configured to use Asymmetric Logical Unit Access (ALUA) to the computer that has multiple active paths.
  • Multiple active paths fail.
In this scenario, the I/O operation fails, and the storage device is no longer accessible.


To resolve this issue, we have released a hotfix. Even though this issue has only been observed in Windows Server 2008 R2, the hotfix also applies to Windows 7.

Important If you install a language pack after you install this hotfix, you must reinstall this hotfix. Therefore, we recommend that you install any language packs that you need before you install this hotfix. For more information, see Add language packs to Windows.

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 this specific problem.

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, submit a request to 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.


To apply this hotfix, you must install Service Pack 1 for Windows 7 or 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 may have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.
File information


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


See the terminology that Microsoft uses to describe software updates.

आलेख ID: 3070714 - पिछली समीक्षा: 27/07/2015 - संशोधन: 1