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Thursday, June 19, 2008

NTFS links - reparse, symbolic, hard, junction

Reading through various Microsoft documents, it seems several terms have been adopted to describe methods of linking one NTFS object to another in different scenarios. I tried and couldn't find a single description of the different methods; therefore below you'll find my interpretation, mostly describing how they link to each other, and the tools available to manage the links.

  • Reparse Point File - user-defined data, interpreted by a file sytem filter, eg. RIS SIS, Microsoft RSS
  • Reparse Point Directory - Map a local folder to any other local folder on or across local volumes, eg c:\windows\temp mapped to c:\temp
  • Hard Link File - filesystem link linking one file to another, linking a file object to one or more directory entries.
  • NTFS Junction Point Directory -> Reparse Point Directory
  • Directory Symbolic Link -> NTFS Junction Point Directory
  • Volume Mount point -> Directory Symbolic Link mapping the root of one local volume to a folder in another local volume
  • Soft Link Directory -> NTFS Junction Point Directory -> Reparse Point Directory
  • NTFS Junction Point Files -> Reparse Point File
  • Symbolic Directory Links -> NTFS Junction Point Directory
  • Symbolic File Links Matching Unix symbolic link (soft link) functionality with absolute file, relative file in local -> local, local -> remote, remote -> local and remote -> remote combinations, available in Vista and 2008.

Tools to manage links:

  • linkd.exe (2000 resource kit) - Create NTFS Junction Points (the source directory must be empty)
  • mountvol.exe (2000 CD-rom) - Manage directory symbolic links deisnged to mount a volume (which may or may not have a drive letter already associated) bypassing 26 drive letter limitations
  • delrp.exe (2000 resource kit) - Delete NTFS junction points and other types of reparse points
  • junction.exe (sysinternals) - Create or delete NTFS Junction points (reparse points). Note that you can create a junction that maps a directory to a file target, it just doesn't achieve much.
  • fsutil.exe hardlink (oem with XP/2003) - Create hard file links
  • fsutil.exe reparsepoint (oem with XP/2003) - Query or delete reparse points
  • mklink - Vista/2008 utility to create symbolic directory and file links, hard links and directory junctions

References:

Symbolic links:
http://msdn.microsoft.com/en-us/library/aa365680(VS.85).aspx

Getting the free space available under a certain directory
http://blogs.msdn.com/adioltean/archive/2006/01/31/521551.aspx

Creating Symbolic Links
http://msdn.microsoft.com/en-us/library/aa363878(VS.85).aspx

Junction utility:
http://www.microsoft.com/technet/sysinternals/FileAndDisk/Junction.mspx

Creating Symbolic Links
http://msdn.microsoft.com/en-us/library/aa363878(VS.85).aspx

How to create and manipulate NTFS junction points
http://support.microsoft.com/?kbid=205524

Reparse Point Support in Windows 2000-Based Clusters
http://support.microsoft.com/kb/262797

Hard Links and Junctions
http://msdn.microsoft.com/en-us/library/aa365006(VS.85).aspx

Reparse Points
http://msdn.microsoft.com/en-us/library/aa365503(VS.85).aspx

Symbolic Linking
http://technet2.microsoft.com/windowsserver2008/en/library/5c7ffdb9-7066-4bdf-bc7d-eded8db2ce821033.mspx?mfr=true

Reparse Point Support in Windows 2000-Based Clusters
http://support.microsoft.com/kb/262797

How to create and manipulate NTFS junction points
http://support.microsoft.com/?kbid=205524

Fsutil: hardlink
http://technet2.microsoft.com/windowsserver/en/library/185f86b0-62c0-4fc8-b49b-ff76f2db21c81033.mspx?mfr=true

File-Based Symbolic Links
http://technet.microsoft.com/en-us/magazine/cc162494.aspx



Wayne's World of IT (WWoIT), Copyright 2008 Wayne Martin.

1 comment:

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About Me

I’ve worked in IT for over 20 years, and I know just about enough to realise that I don’t know very much.