Support for Microsoft SQL Server 2000 data storage on mounted drives varies, depending on whether an instance of SQL Server 2000 is a stand-alone instance or a clustered instance. A stand-alone instance does not use failover clustering. A clustered instance does use failover clustering. More information about each type of instance follows.

Stand-alone instance

On a stand-alone instance of SQL Server 2000, data storage on mounted drives is supported on Microsoft Windows 2000 and on Microsoft Windows Server 2003. However, the SQL Server 2000 Setup program requires the base drive of a mounted drive to have an associated drive letter. If the base drive of a mounted drive does not have an associated drive letter, the Setup program will assign the next available drive letter to the drive. However, if all the drive letters are already assigned, the Setup program will fail.

For more information about SQL Server requiring a drive letter when you use mounted drives, click the following article number to view the article in the Microsoft Knowledge Base:

Clustered instance

On a clustered instance of SQL Server 2000, data storage on mounted drives or on NTFS junction points is not supported. This applies to Windows 2000 and to Windows Server 2003. The installation of SQL Server 2000 is not supported on a clustered configuration that has mounted drives even if the mounted drives are not intended to be used with SQL Server. That is, if a configuration already has some mounted drives for file shares, you cannot install SQL Server on that configuration, even if you are not using the mounted drives for SQL Server.

SQL Server 2005 failover clustered instances fully support mounted drives if the mounted drive is hosted by a cluster drive with a drive letter assigned.

Note Because of the number of available drive letters, the number of the virtual instances on a cluster is limited to 23. SQL Server 2005 has the same limitation.

The SQL Server 2005 resource depends on the SQL network name resource and the physical disk resources that hold its data. When mount points are being used together with the physical disks, each mount point must appear as a cluster resource. Additionally, each mount point must also be added as a SQL Server dependency. If only the root physical disks dependency is added and the mount points are not added, database corruption will occur on failover. Database corruption may also occur when SQL Server is restarted without failing over.

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A mounted drive is a volume or a drive that is mapped to a folder on a volume that uses the NTFS file system. Mounted drives function as any other volume or drive. A mounted drive is assigned a drive path instead of a drive letter.

Mounted drives are sometimes referred to as "mounted volumes," as "mount points," as "mountpoints," or as "volume mount points." You can create mounted drives by using the Microsoft Windows 2000 Disk Management snap-in or by using the Mountvol.exe file.


Although mounted drives are a feature of Windows 2000, mounted drives are not supported on Windows 2000 cluster servers because of the failover behavior on Windows 2000 clustered servers for mounted drives and because of the assignment of different GUIDs for each disk on each node. The behavior of mounted volumes on a failover cluster was fixed for Windows Server 2003. Windows Server 2003 supports mounted drives in a cluster. However, because of limitations in SQL Server 2000, the use of mounted volumes on a clustered instance of SQL Server 2000 is not supported on any operating system.

A SQL Server 2000 installation is not supported on a clustered configuration with mounted drives because SQL Server 2000 was released before the mounted drive feature was released. The code that is used to enumerate the shared and the common local fixed disks in SQL Server 2000 in a clustered configuration is not compatible with mounted drives.

Because of similar limitations, an upgrade of a clustered instance of SQL Server is not supported. An installation of SQL Server service packs on a clustered instance of SQL Server is also not supported.

Note The information in this article supercedes the information that is in the Microsoft Press book "SQL Server 2000 High Availability" that was published before this discovery. The information that is superceded is in "Chapter 4 - Disk Configuration for High Availability" in the "Part II - Microsoft SQL Server Technology" section.

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For more information about mounted drives, click the following article numbers to view the articles in the Microsoft Knowledge Base: For more information about volume mount points, visit the following Microsoft Web site:For additional information about mounted drives, see the "Windows Server 2003 Help" topic, the “Disks and Data” topic, the “Managing Disks and Data” topic, the “Disk Management” topic, and the “Using NTFS Mounted Drives” topic in Windows Help Online.

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