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Q107651: 32-Bit File Access Can Cause ScanDisk to Report Harmless Error

Article: Q107651
Product(s): Microsoft Windows 3.x Retail Product
Version(s): MS-DOS:6.2,6.22; WINDOWS:3.11
Operating System(s): 
Keyword(s): kbbuglist
Last Modified: 01-OCT-1999

3.11    | 6.20 6.22
WINDOWS | MS-DOS
kbtool kberrmsg kbbuglist

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The information in this article applies to:

- Microsoft Windows for Workgroups version 3.11 
- Microsoft MS-DOS operating system versions 6.2, 6.22 
-------------------------------------------------------------------------------

SYMPTOMS
========

After you run Windows for Workgroups version 3.11 on an MS-DOS 6.2
DoubleSpace-compressed drive or an MS-DOS 6.22 DriveSpace-compressed drive with
32-bit file access enabled, the MS-DOS ScanDisk utility may report the following
error when run at the MS-DOS command prompt

  ScanDisk found <nnnn> bytes of data on drive <x> that might be
  one or more lost files or directories, but which is probably just taking up
  space.

where <nnnn> equals the number of bytes of lost files or directories, and
<x> equals the logical drive ScanDisk was scanning.

NOTE: ScanDisk should not be run from the MS-DOS command prompt within Microsoft
Windows or Windows for Workgroups. It should be run directly from MS-DOS. If you
must run ScanDisk from within Windows, use the /CHECKONLY switch. This switch
prevents ScanDisk from attempting to repair any damage while Windows is running.

CAUSE
=====

This error message is caused by a problem in Windows for Workgroups 3.11. 32-bit
file access writes buffers in the order they are used, meaning the first
information into the buffer is the first information out. 32-bit file access
also tries to improve access speed by finding contiguous used buffers and
writing them together. If these two optimization schemes both try to clean the
buffer simultaneously, an erroneous extra entry in the DoubleSpace or DriveSpace
file allocation table (MDFAT) can occur.

This problem can also occur when 32-bit file access flushes the entire volume.
Buffers are written sequentially according to their physical location. This
optimization has no effect on a compressed volume (since there is no
physical-to-logical relationship) and can result in erroneous entries in the
MDFAT.

RESOLUTION
==========

No saved data is lost. However, data in memory only at the time of the error
message may be lost. If you choose to correct the problem, ScanDisk repairs the
volume and creates the standard CHKDSK files (FILEnnnn.CHK), which can be
deleted. ScanDisk may also report that there are sections of the DoubleSpace or
DriveSpace volume not being used by any files but marked as unusable; it can
repair these as well.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Windows for Workgroups
version 3.11. We are researching this problem and will post new information here
in the Microsoft Knowledge Base as it becomes available.

Additional query words: 3.11 6.20 6.22 vfat mdfat lost entry dblspace drvspace drivespace

======================================================================
Keywords          :  kbbuglist
Technology        : kbAudDeveloper kbWFWSearch kbWFW311 kbMSDOSSearch kbMSDOS622 kbMSDOS620
Version           : MS-DOS:6.2,6.22; WINDOWS:3.11

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