Microsoft KB Archive/71609

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Errors Caused by Cross-Linked Files or Lost Clusters

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Q71609

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The information in this article applies to:


 * Microsoft Windows versions 3.0, 3.0a, 3.1, 3.11
 * Microsoft MS-DOS operating system versions 3.1, 3.2, 3.21, 3.3, 3.3a, 4.0, 4.01, 5.0, 6.0

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SYMPTOMS
In Windows 3.0, you receive an unrecoverable application error (UAE) or a &quot;Violated System Integrity&quot; error when you try to access a file. In Windows 3.1 enhanced mode, your system stops responding (hangs) when you try to access a file. In either Windows version, printer output may be garbled.

CAUSE
These symptoms may indicate that you have cross-linked files or lost clusters (or allocation units).

WORKAROUND
Running the MS-DOS CHKDSK utility (CHKDSK.COM) can identify these problems and, optionally, correct them. The following is the correct syntax for running the CHKDSK command

"CHKDSK [ :] [ ] [/F] [/V]" where:


 * specifies the drive is to be analyzed.
 * allows the specification of a particular directory and file type using wildcard characters.
 * /F tells MS-DOS to repair any errors found.
 * /V echoes the filename(s) as they are being checked.

The parameters enclosed in brackets ([]) are optional. If you use these parameters, type them without the brackets.

Parameters enclosed in angle brackets (<>) are variables. Substitute actual values for these variables. For example, substitute

"C:" for:

":" WARNING: Before using CHKDSK, exit Windows. You should NEVER run this utility with the /F parameter from Windows; doing so corrupts files on the hard disk.

CAUTION: Running CHKDSK/F on a hard drive with a large number of lost clusters may result in damaged files, loss of data, and the loss of directory integrity. For more information regarding CHKDSK, please read the &quot;Microsoft MS-DOS User's Guide and User's Reference&quot; (pages 44-45 for version 4.01 and pages 381-383 for version 5.0).

Cross-Linked Files
Cross-linked files occur when two or more files have been allocated the same cluster. One or both of the files may contain information belonging to the other.

NOTE: If you are using Undelete and the Delete Sentry method of protection, remove the memory-resident portion of Undelete by typing undelete /unload at an MS-DOS command prompt before you delete any cross-linked files.

Lost Clusters
Lost clusters occur when a file is deleted from the directory listing, but the file allocation table (FAT) still shows the clusters allocated to the file.

The CHKDSK utility asks if you want the lost clusters converted to a file. If you answer &quot;Yes,&quot; these clusters are allocated to a file named FILE .CHK, where is a number. This file appears in the root directory of the drive. If you answer &quot;No,&quot; the lost clusters are deallocated and are available for use again.

CHKDSK Command
The MS-DOS CHKDSK command checks the directory structure and the FAT for inconsistencies such as the following:


 * Invalid pointers to data areas
 * Bad file attributes in directory entries
 * Damage to a portion of the directory that makes it impossible to check one or more paths
 * Damage to an entire directory that makes the files contained in that directory inaccessible
 * Defective disk sectors in the FAT
 * Invalid cluster (disk allocation unit) numbers in the FAT
 * Lost clusters (clusters are identified that are not assigned to a file)
 * Cross-linking of files on the same cluster (more than one file has been assigned the same cluster)