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Invalid MSDOS Function error on Windows copying a file from a UNIX or Linux VOB

Technote (troubleshooting)


This technote discusses why the error, Invalid MSDOS Function occurs when copying data from an IBM® Rational® ClearCase® VOB stored on UNIX® or Linux® to a Microsoft® Windows® client.


When copying files from a dynamic view in Windows Explorer to a location on the local filesystem (or outside of a ClearCase view), the following error occurs:

Invalid MSDOS function

In the ClearCase error logs, several errors similar to the following are seen:

Null VOB handle passed to libvob routine.

Internal Error detected in "./..\map_db.c" line 528

This occurs intermittently, and for different files with different users.

This problem is in the Windows to UNIX or Linux interoperation environment.


The mnode settings are set higher than 800 for the client machines in question.

Resolving the problem

Adjust the mnode settings as follows:

  1. Go to Start (> Settings) > Control Panel > double-click the ClearCase icon > click the MVFS Performance tab:

  2. If the value in either of the following fields is set to a value higher than 800, change the existing value to 800 and reboot:
    • Maximum number of mnodes to keep on the VOB free list
    • Maximum number of mnodes to keep on the cleartext free list

Related information

Invalid MS-DOS function error copying files on Windows

Cross Reference information
Segment Product Component Platform Version Edition
Software Development Rational ClearCase Interop

Document information

More support for: Rational ClearCase

Software version: 2003.06.00

Operating system(s): Windows

Reference #: 1128365

Modified date: 10 June 2008