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From: ESC1111%DDAESA10.BITNET@wiscvm.wisc.edu (N.Head)
Newsgroups: comp.os.minix
Subject: Re: bad blocks on hard disk
Message-ID: <492@louie.udel.EDU>
Date: Wed, 9-Sep-87 03:07:33 EDT
Article-I.D.: louie.492
Posted: Wed Sep  9 03:07:33 1987
Date-Received: Thu, 10-Sep-87 07:04:45 EDT
Sender: mmdf@udel.EDU
Lines: 20

Andy asked does the DOS format program mark bad sectors properly ::
Yes and no. The low level format supplied with the AT diagnostics does
write info to the disk (a using a controller format option I believe) to
ensure that bad blocks return a bad read status continually and reliably.

The FORMAT program supplied with DOS doesn't do this - it only marks the
block as bad in the File allocation table so that DOS never allocates it
to a file. Unfortunately MINIX takes no notice of the FAT :-) !!

Neither one or the other of these approaches will do anything sensible about
sectors which go bad during use of the system (short of doing a low level
format).

It would be possible to reformat a track 'on the fly' if a bad sector was found
(save the data that could still be read, use the BIOS format track service on
the offending track, restore the data, moving the data from the bad sector
s'where else). I know I don't have to time to get into that though ...

All this was from the viewpoint of an AT. Anyone know about PC's ??
Nigel.