Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!ihwpt!knudsen
From: knudsen@ihwpt.ATT.COM (mike knudsen)
Newsgroups: comp.sys.m6809
Subject: Suggestion for an OS9 utility
Keywords: Bad Disk Sectors
Message-ID: <2265@ihwpt.ATT.COM>
Date: 20 Jan 88 19:23:42 GMT
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 36

I'd like to find, or get help to write, a simple (?)
utility that would read thru an entire diskette and
find all the bad (as in unreadable) sectors and mark
them as in-use on the sector allocation bitmap so that
they would never be assigned to any future files.

Options from the command line would control:
*what to do if a bad sector is already allocated
(at least type warning; better to find what file it belongs
to; maybe unlink it from that file);

*whether to try and re-format just each bad sector (write
some pattern on it and try to re-read it.  If this works,
then media itself is not [quite as] faulty.)

*whether to create a single file in the root directory,
named BAD.SECTORS, which would contain all the baddies.
(I dislike this, since now a user could DEL that file
and have all those bad sectors "loose" again.)

I know that FORMAT is supposed to identify bad sectors when a
disk is first formatted and set their allocation bits.
However, I often find bad sectors showing up later,
especially on DS80-track disks.

I know how to read thru all the sectors (open /Dn@),
but need some serious study of the allocation bitmap
area.  Also I assume it's very hard to find what file
a given sector belongs to -- must search every file in every
directory.  Or is there a faster way?  I know DCHECK
can identify files with duplicate sectors, but I assume
it starts with a recursive descent thru the directory tree anyway.
-- 
Mike J Knudsen    ...ihnp4!ihwpt!knudsen  Bell Labs(AT&T)
    Delphi: RAGTIMER    CIS: <memory failure, too many digits>
	"Just say NO to MS-DOS!"	"OS/2 == 1/2 of an OS"