Open Software Solutions

Consider the following scenario:

•	Windows Server 2008 is running on a computer that supports the Hot Add Processor feature.
•	The computer uses multipath I/O (MPIO) disks.
•	You use the Hot Add Processor feature to add a new CPU to the computer, or you use the PnpCPU.exe tool to simulate hot addition of a new CPU.

In this scenario, the MPIO disks may disappear from the system.

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This problem occurs because the status of the MPIO disks is not updated as expected during plug-and-play resource rebalance.

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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. 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, 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 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. To create a separate service request, visit the following Microsoft Web site:

Note The Hotfix download available section and the online request forms display 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

No prerequisites are required.

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, 32-bit editions

File name	File version	File size	Date	Time	Platform
Package_1_for_kb951590~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,776	19-Apr-2008	17:34	Not Applicable
Package_2_for_kb951590~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,943	19-Apr-2008	17:34	Not Applicable
Package_3_for_kb951590~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,781	19-Apr-2008	17:34	Not Applicable
Package_4_for_kb951590~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,781	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_client_1~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,367	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_client~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,431	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_sc_0~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,421	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_sc~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,423	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_server_0~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,425	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_server~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,431	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_winpesrv_0~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,422	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_winpesrv~31bf3856ad364e35~x86~~6.0.1.0.mum	Not Applicable	1,429	19-Apr-2008	17:34	Not Applicable
X86_fedb605b00b19a1c71f8c76eba0f5dd4_31bf3856ad364e35_6.0.6001.22162_none_9a8a9bdc1f5bd4bf.manifest	Not Applicable	696	19-Apr-2008	17:34	Not Applicable
X86_microsoft-windows-classpnp_31bf3856ad364e35_6.0.6001.22162_none_15cdec72c55e4f60.manifest	Not Applicable	4,355	18-Apr-2008	05:46	Not Applicable
Classpnp.sys	6.0.6001.22162	127,544	18-Apr-2008	05:33	x86
Stortrace.mof	Not Applicable	17,937	18-Dec-2007	21:09	Not Applicable

Windows Server 2008, 64-bit editions

File name	File version	File size	Date	Time	Platform
Amd64_a4c6d13947978089f5a07126a33242c3_31bf3856ad364e35_6.0.6001.22162_none_f06c64be09febed9.manifest	Not Applicable	700	19-Apr-2008	17:34	Not Applicable
Amd64_microsoft-windows-classpnp_31bf3856ad364e35_6.0.6001.22162_none_71ec87f67dbbc096.manifest	Not Applicable	4,361	18-Apr-2008	06:55	Not Applicable
Package_1_for_kb951590~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,786	19-Apr-2008	17:34	Not Applicable
Package_2_for_kb951590~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,955	19-Apr-2008	17:34	Not Applicable
Package_3_for_kb951590~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,791	19-Apr-2008	17:34	Not Applicable
Package_4_for_kb951590~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,791	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_client_1~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,375	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_client~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,439	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_sc_0~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,429	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_sc~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,431	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_server_0~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,433	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_server~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,439	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_winpesrv_0~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,430	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_winpesrv~31bf3856ad364e35~amd64~~6.0.1.0.mum	Not Applicable	1,437	19-Apr-2008	17:34	Not Applicable
Classpnp.sys	6.0.6001.22162	165,432	18-Apr-2008	06:44	x64
Stortrace.mof	Not Applicable	17,937	18-Dec-2007	21:10	Not Applicable

Windows Server 2008, Itanium-based versions

File name	File version	File size	Date	Time	Platform
Ia64_0428ad75595bfd6945858b8c87a8a2d6_31bf3856ad364e35_6.0.6001.22162_none_ac97a9cc819d98e0.manifest	Not Applicable	698	19-Apr-2008	17:34	Not Applicable
Ia64_microsoft-windows-classpnp_31bf3856ad364e35_6.0.6001.22162_none_15cf9068c55c585c.manifest	Not Applicable	4,358	18-Apr-2008	11:45	Not Applicable
Package_1_for_kb951590~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,781	19-Apr-2008	17:34	Not Applicable
Package_2_for_kb951590~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,786	19-Apr-2008	17:34	Not Applicable
Package_3_for_kb951590~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,786	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_sc_0~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,425	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_sc~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,426	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_server_0~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,429	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_server~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,434	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_winpesrv_0~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,426	19-Apr-2008	17:34	Not Applicable
Package_for_kb951590_winpesrv~31bf3856ad364e35~ia64~~6.0.1.0.mum	Not Applicable	1,433	19-Apr-2008	17:34	Not Applicable
Classpnp.sys	6.0.6001.22162	346,168	18-Apr-2008	10:36	IA-64
Stortrace.mof	Not Applicable	17,937	18-Dec-2007	21:09	Not Applicable

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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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PnpCPU.exe is a command-line tool that simulates the hot addition of processors to a running instance of Windows Server 2008. This tool is included in the Windows Driver Kit (WDK). For more information, visit the following Microsoft Web site:

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

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