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From: guardian@laidbak.UUCP (Harry Skelton)
Newsgroups: comp.os.minix
Subject: Re: bad blocks on hard disk
Message-ID: <1135@laidbak.UUCP>
Date: Fri, 4-Sep-87 12:49:21 EDT
Article-I.D.: laidbak.1135
Posted: Fri Sep  4 12:49:21 1987
Date-Received: Sat, 5-Sep-87 20:13:28 EDT
References: <196@turbo.RAY.COM> <489@ast.cs.vu.nl>
Reply-To: guardian@laidbak.UUCP (Harry Skelton(E))
Organization: LAI Chicago
Lines: 33

In article <489@ast.cs.vu.nl> ast@cs.vu.nl () writes:
>In article <196@turbo.RAY.COM> jim@turbo.RAY.COM (Jim Shaw x8232) writes:
>>...  I have a couple of known bad tracks ...
>
>I haven't done anything in this area, but I agree it is important.  If
>someone who knows how DOS does it could modify the 1.2 xt_wini.c and
>1.2 at_wini.c to handle bad tracks the DOS way (for compatibility) that
>would no doubt be useful to many people.  Probably what you have to do
>
>Andy Tanenbaum (ast@cs.vu.nl)

As far as I know, there are two methods of bad track mapping that I have 
"bumped" into.  The first is from the HD OEM that created the controler
card.  Some are smart enough to have the bad track map somewhere on disk
that the OS doesn't touch (nice).  The old Datamac hard disks do this and
my current Xebec Controler will do this.

The other method is to keep track of bad tracks either in a table much like
the file system table or mark the sectors as 'bad/reserved/whatever' so the
OS does not touch them.  This is done under DOS with the program 'scavenger'.
(PD Utility - dos format is pretty dumb)

I beleive that SCO makes a device that is a pointer to the bad track table
and the OS has to check the table before it writes to a sector or something
like that.  

The end result is a table or marker to tell the OS that the sector/track is
bad.  Better a sector as a track can chew up good sectors.

?How bout a badtrack program and a mod to minix to have a bad_sector flag?
/dev/hd (you can tell I don't play with minix) can be a list of sectors
that are good and skipping the bad 'blocks' as needed or setup with
'badtrack'  ??? Ideas ???