Windows 2000 breaks the 26 drive letter limitation

by Wayne Maples [Published on 20 April 2004 / Last Updated on 20 April 2004]

With Windows 2000 NTFS junction points you can surpass the 26 drive letter limitation with directory symbolic links, where a directory serves as a symbolic link to another directory on the computer. These symbolic links, reparse links, allow any Windows 2000 folder to be mounted at any point. Additionally any number of volumes can be mounted using mountvol.exe. Reparse points are the underlying mechanism on which NTFS junctions are based, and they are also used by Windows 2000's Remote Storage Service. Without duplicating files and eating up dasd, you could have a folder and its directory tree mounted in one or more other locations.

The junction point tools are:

linkd.exe which is used to create/delete junction folders onto Windows 2000 NTFS and is found in the Windows 2000 Resource Kit. LinkD grafts (links) the target name directly into the name space at Source, so that Source subsequently acts as a name space junction. The Source directory must reside on a disk formatted with NTFS in Windows 2000. The destination (the target of the link) can be any valid directory name or device name or valid object name in Windows 2000.

Mountvol.exe which mounts/unmounts the root folder of a local volume onto a Windows 2000 version of NTFS folder, that is, mounts/unmounts the volume. Mountvol.exe is in the I386 of the Windows 2000 CD.

Delrp.exe deletes reparse points, which are the entities underlying junction points and is part of the Windows 2000 Resource Kit. Delrp.exe seems like linkd.exe but has particular value for developers whereas linkd is an administrators utility.

System Internals have written a freeware junction utility, junction which duplicates linkd's capability to create reparse points but also allows one to browse and see whether a folder is a folder or a symbolic link, that is a reparse junction. I strongly recommend that you periodically check System Internals since they do such a wonderful job supplying valuable freeware and commercial utilities of great value to Windows NT administrators.

It is apparent that the underlying technology of reparse points is very powerful and gives Windows 2000 tremendous capabilites. These junctions allow I/O redirection, name space reloading and other capabilities. This technology built into Windows 2000 provides hierarchial storage management. Unused files could be archived to tape or removable drives. When one tries to access an archived file or folder, the reparse point could mount the archival media for retrieval. I suspect there are lots of other capabilities inherent in the technology.

Microsoft kb related articles:
How to Create and Manipulate NTFS Junction Points
Disk Space Reporting Does Not Include Junction Point Targets
Usage of NTFS 5.0 Junctions in the Sysvol Folder
SIS Does Not Operate on File Located in Mount Point or Junction
Cannot Open Files After Removing Remote Storage Service
How Single Instance Storage Identifies Which Volumes to Manage

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