A hotfix is available that provides a mechanism for DSM to notify MPIO that a particular path is back to online in Windows Server 2008 and Windows Server 2008 R2

Introduction

This article describes a hotfix that provides a mechanism for Microsoft Device Specific Module (DSM) to notify Microsoft Multipath I/O (MPIO) that a particular path is back online. This hotfix adds a new notification type to the existing DsmNotification interface.

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: 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.


Notes for third-party DSM developers

If you want to implement your own DSM provider together with MS MPIO, and you want to configure PathOnLine notification type that is introduced in this update, follow the following syntax:

For the new PathOnline notification type, the DsmNotification interface takes these additional parameters: PathId (PVOID), DsmId (PVOID), Status (PNTSTATUS).

Prerequisites

To apply this hotfix, you must be running Windows Server 2008 Service Pack 2 (SP2) or Windows Server 2008 R2 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 2008

For more information about how to obtain a Windows 7 or 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 apply this hotfix, 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

Status

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

More Information

When a path failure is reported by the DSM, the MPIO marks the path as failed and schedules a path recovery worker thread. If the path is back online, the DSM recognizes it as a valid path and may return the path of the MPIO. However, if the recovery worker thread of the path does not run, the path is still marked as failed. Therefore, a delay occurs when the MPIO handles the I/O requests.

After you apply this hotfix, the DSM can notify the MPIO to clear the failure mark on a path that is back online.

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
Proprietà

ID articolo: 2754704 - Ultima revisione: 08 feb 2014 - Revisione: 1

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