Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!beartrk!cjp
From: cjp@beartrk.beartrack.com (CJ Pilzer)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Probable NON-DOS Disk
Summary: How to fix NON-DOS error
	 ]
Message-ID: <413@beartrk.beartrack.com>
Date: 1 Jul 90 05:53:19 GMT
References: <e7b9ac1e186726895f00@canremote.uucp>
Organization: Bear Track Computer Co., Takoma Park, MD.
Lines: 27

In article <e7b9ac1e186726895f00@canremote.uucp>, jack.lupic@canremote.uucp (JACK LUPIC) writes:
> P Message entered 1990 06 26  22:31 P
> 
> I have a Segate ST251-1 partitioned into 3 logical drives.Recently
> and when I run CHKDSK,it reports on my Drive D:\ <second partition>
> "Probable NON-DOS Disk,Continue Y/N".This is under DOS 4.01.
A report of a PROBABLE NON-DOS PARTITION is almost always an indication
that the media descriptor byte of the partition or disk is corrupted.
This byte is located in three places on your disk:

	Sector 0, Offset 21 of the Boot Record
	Sector 1, Offset 0 of the FAT 1
	Offset 0 in the 1st sector of FAT 2

This byte should be hex F8 for a hard disk.  You can fix this with several
utilities such as the Norton Utilities.  Full instructions are included on
page 108 of the Norton Troubleshooter, a pamphlet included with the Norton
Utilities.  You could of course use any other sector editor.

However, you really want to know what caused this problem to avoid any more
serious damage to your data.  One way to do this is to fix the corrupted 
byte.  Then keep a record of what you are doing between reasonably often
runs of CHKDSK.  If you get the error message agian, you know that it was
caused by something that occurred between that run and the last clear run
of CHLDSK.

-- cj