Why does MS-DOS BACKUP introduce CHKDSK errors?
Jay F. Rosenberg
I just performed a full hard disk (10 MB) backup using MS-DOS
BACKUP command (BACKUP C:\ A:/S) on my Compaq Plus. Before doing the
backup, CHKDSK told me that my directory structure was in order. After
doing the backup, CHKDSK told me that I had an allocation error in one small
file in a subdirectory; adjusted the size; then told me that I had one lost
cluster in 1 chain and that that file was now cross linked to another in a
different subdirectory on cluster 512 (in both files).
Well, I tidied all that up, but what I want to know is: How and why
did it happen? I would have thought that making a backup involved only
*reading* directories, not fiddling with them, so how did things get
changed? Also, are my backup disks likely to be in order? How can I tell?
(I'm not about to reformat C: and restore just to find out!)
Thanks in advance for any help.
JAY ROSENBERG Dept. of Philosophy UNC Chapel Hill, NC 27514
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Kenneth R. Ballou
>
>... I would have thought that making a backup involved only
>*reading* directories, not fiddling with them, so how did things get
>changed?
One of the attribute bits associated with a file is the 'archive' bit. It
is set when a file is created or modified. Its purpose is to indicate to
BACKUP any files changed since the last backup. Hence, BACKUP clears this
bit as it churns (all right, crawls) along; this indeed involves writing
in directories (indirectly, using some DOS function).
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Kenneth R. Ballou ...!ucbvax!brahms!ballou
Dept. of Mathematics bal...@brahms.berkeley.EDU
University of California
Berkeley, California 94720