Multiple-path software may cause disk signature to change

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

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.

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 Web site: 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.

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.

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

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:

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: