Multiple-path software may cause disk signature to change (293778)

SYMPTOMS

The disk signature and Global Unique Identifier (GUID) for a disk may change unexpectedly on computers that have redundant Host Bus Adapters (HBA) to a common external disk. In this case, programs that depend on these disk signatures in the master boot record (MBR) may fail.

Windows Clustering uses the disk signatures and their GUIDs to mount disks and to bring the disks online. If the disk signature changes, the disks may fail, and the following error message may be logged in Event Viewer:

Event ID: 1034
Source: ClusDisk
Description: The disk associated with cluster disk resource DriveLetter could not be found. The expected signature of the disk was DiskSignature.

Another symptom of changed volume GUIDs or the disk signature may be that drive letters may be reassigned (reordered) after a restart.

CAUSE

This issue can occur if you have configured the multiple-path software incorrectly or if this software malfunctions. For additional redundancy, you can add multiple controllers to access an external disk. Multiple-path software controls these two controllers, and makes them seem to be a single controller to the operating system. Multiple-path software also makes the disk seem like a single drive to the operating system. If this software presents the same disk to Windows 2000 twice (one representation from each controller), issues can occur. If Ftdisk detects a 0 (zero) or duplicate disk signature, then it writes a new signature without prompting or notifying the user.

You must change the signature immediately because Ftdisk cannot report the same unique ID (which is composed of the signature and partition offset) to Mount Manager (Mountmgr). When Mountmgr sees a new unique ID, it creates a new volume GUID and a fresh drive letter assignment for that new volume.

RESOLUTION

Hotfix information

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows 2000 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.Prerequisites No prerequisites are required. 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 tool in Control Panel.

Date         Time  Version        Size     File name 
-----------------------------------------------------
10-May-2004  17:44 5.0.2195.6920  116,400  Ftdisk.sys

MORE INFORMATION

This hotfix is included in the list of recommended hotfixes to be proactively applied to Windows 2000 server clusters. Click the following article number to view the article that contains this list in the Microsoft Knowledge Base:

895090 Recommended hotfixes for Windows 2000 Service Pack 4-based server clusters

This hotfix should be evaluated and applied proactively to all server clusters that are prone to be negatively affected by the problem that is described in this article.

For more information about how hotfix packages are named, click the following article number to view the article in the Microsoft Knowledge Base:

816915 New naming schema for Microsoft Windows hotfix packages