Open Software Solutions

Consider the following scenario:

•	You are running a Windows Server 2008-based computer.
•	You expose to the computer an iSCSI logical unit number (LUN) that is using the Microsoft Multipath I/O (MPIO) solution.
•	You enable the MPIO feature on the iSCSI option.
•	You unmap the LUN from the computer, and then you remap the LUN to the same computer.

When you use the Microsoft Device Specific Module (DSM) that plugs into the MPIO in this scenario, you experience a nonpaged pool memory leak.

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This issue occurs because the MPIO structures are not freed after the LUN performs the disconnect and delete operations that are associated with the unmapping and remapping process.

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Hotfix information

A supported hotfix is now 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. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows Server 2008 Service Pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

Note If additional issues occur or 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. To create a separate service request, visit the following Microsoft Web site:

Prerequisites

To apply this hotfix, you must have Windows Server 2008 installed.

Important Any existing LUNs that are claimed by the DSM may become orphaned after you apply this hotfix. To resolve the issue, follow these steps:

1.	Before you apply the hotfix, export the following registry key to a .reg file: HKEY_LOCAL_MACHINE System CurrentControlSet Services MSDSM Parameters
2.	After the hotfix has been applied, import the .reg file to the computer.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2008, x86 version

File name	File version	File size	Date	Time	Platform
Package_1_for_kb952263~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,972	15-May-2008	17:52	Not Applicable
Package_2_for_kb952263~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,810	15-May-2008	17:52	Not Applicable
Package_3_for_kb952263~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,810	15-May-2008	17:52	Not Applicable
Package_for_kb952263_client_1~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,367	15-May-2008	17:52	Not Applicable
Package_for_kb952263_client~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,430	15-May-2008	17:52	Not Applicable
Package_for_kb952263_sc_0~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,421	15-May-2008	17:52	Not Applicable
Package_for_kb952263_sc~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,422	15-May-2008	17:52	Not Applicable
Package_for_kb952263_server_0~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,425	15-May-2008	17:52	Not Applicable
Package_for_kb952263_server~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,430	15-May-2008	17:52	Not Applicable
Update.mum	Not Applicable	2,580	15-May-2008	17:52	Not Applicable
X86_msdsm.inf_31bf3856ad364e35_6.0.6001.22179_none_ca8e32a5f4d9d8ed.manifest	Not Applicable	1,664	15-May-2008	17:54	Not Applicable
Msdsm.sys	6.0.6001.22179	94,776	15-May-2008	07:36	x86

Windows Server 2008, x64 version

File name	File version	File size	Date	Time	Platform
Amd64_msdsm.inf_31bf3856ad364e35_6.0.6001.22179_none_26acce29ad374a23.manifest	Not Applicable	1,666	15-May-2008	17:56	Not Applicable
Package_1_for_kb952263~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,984	15-May-2008	17:52	Not Applicable
Package_2_for_kb952263~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,820	15-May-2008	17:52	Not Applicable
Package_3_for_kb952263~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,820	15-May-2008	17:52	Not Applicable
Package_for_kb952263_client_1~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,375	15-May-2008	17:52	Not Applicable
Package_for_kb952263_client~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,438	15-May-2008	17:52	Not Applicable
Package_for_kb952263_sc_0~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,429	15-May-2008	17:52	Not Applicable
Package_for_kb952263_sc~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,430	15-May-2008	17:52	Not Applicable
Package_for_kb952263_server_0~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,433	15-May-2008	17:52	Not Applicable
Package_for_kb952263_server~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,438	15-May-2008	17:52	Not Applicable
Update.mum	Not Applicable	2,598	15-May-2008	17:52	Not Applicable
Msdsm.sys	6.0.6001.22179	113,720	15-May-2008	07:31	x64

Windows Server 2008, IA-64 version

File name	File version	File size	Date	Time	Platform
Ia64_msdsm.inf_31bf3856ad364e35_6.0.6001.22179_none_ca8fd69bf4d7e1e9.manifest	Not Applicable	1,665	15-May-2008	17:52	Not Applicable
Package_1_for_kb952263~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,815	15-May-2008	17:52	Not Applicable
Package_2_for_kb952263~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,815	15-May-2008	17:52	Not Applicable
Package_for_kb952263_sc_0~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,425	15-May-2008	17:52	Not Applicable
Package_for_kb952263_sc~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,426	15-May-2008	17:52	Not Applicable
Package_for_kb952263_server_0~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,429	15-May-2008	17:52	Not Applicable
Package_for_kb952263_server~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,434	15-May-2008	17:52	Not Applicable
Update.mum	Not Applicable	1,922	15-May-2008	17:52	Not Applicable
Msdsm.sys	6.0.6001.22179	277,048	15-May-2008	07:31	IA-64

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

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