LAN Manager Fault Tolerance Corrupts Data on Boot Mirror

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Article ID: 112555 - View products that this article applies to.
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The mirroring process for Microsoft LAN Manager produces corruption on the mirror of the boot volume, most noticeably with large (around 40MB) files. There are various symptoms. After unmirroring a drive, large files and their directories may show evidences of corruption: inability to do a directory on C:\PUBLIC when large files reside there, incorrect data on the screen when you use the Type command to display a text file[ASCII 146]s contents. If the drive is unmirrored using FTSETUP, on reboot, CHKDSK finds a number of corrupt files/directories and removes them from the former mirror.


Some casts of longs to shorts in FTDLL.DLL and FTSETUP.EXE caused sector runs of greater than FFFF length to be copied incorrectly to the duplicate drive during the mirroring process, escpecially when drives containing a lot of data were mirrored.


Microsoft has confirmed this to be a problem in LAN Manager versions 2.1, 2.1a and 2.2. A fix to this problem is in development, but has not been regression-tested and may be destabilizing in production environments. Microsoft does not recommend implementing this fix at this time. Contact Microsoft Product Support Services for more information on the availability of this fix.


Article ID: 112555 - Last Review: September 30, 2003 - Revision: 3.0
  • Microsoft LAN Manager 2.1 Standard Edition
  • Microsoft LAN Manager 2.1a
  • Microsoft LAN Manager 2.2 Standard Edition
Retired KB Content Disclaimer
This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.

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