Path: utzoo!censor!geac!jtsv16!uunet!wuarchive!mailrus!iuvax!ux1.cso.uiuc.edu!m.cs.uiuc.edu!wang
From: wang@m.cs.uiuc.edu (Eric Wang)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Accidental formatting of hard disk
Keywords: DOS format
Message-ID: <1989Nov6.001616.25526@ux1.cso.uiuc.edu>
Date: 6 Nov 89 00:16:16 GMT
References: <1197@srhqla.SR.COM>
Reply-To: wang@cs.uiuc.edu (Eric Wang)
Distribution: usa
Organization: University of Illinois, Dept. of Comp. Science, Urbana
Lines: 39

In article <1197@srhqla.SR.COM> tcm@srhqla.SR.COM (Tim Meighan) writes:
>In article <1532@crdos1.crd.ge.COM> davidsen@crdos1.UUCP (bill davidsen) writes:
>
>>command), you may be able to recover some of the data using a package
>>like Norton Utilities. *Do not* put any files back on the disk ifkage
>
>Not a chance.  A high level format writes $F6 into every byte of every
>data sector on the disk.
>
>Tim Meighan

Then the DOS FORMAT command is NOT high-level, by your definition of the term.
IBM just managed to brainwash everybody into thinking that it is.  (Among
those who also swallowed this line: Peter Norton & Paul Mace.)  Mace describes
eloquently in his Guide to Data Recovery how he was just goofing around with
a new hard disk & noticed information surviving multiple formats, which
absolutely staggered him.  After several months of intensive work, he added
UNFORMAT to his Mace Utilities, and Norton and PC-Tools quickly followed his
lead.  As a matter of fact, one of the standard methods to recover data from
a hard disk on the fritz is to reformat it to clean up the corrupted parts,
then unformat it to recover all (?? most, anyways) of the data.  Note that
the process is not guaranteed to be completely successful, but it's better
than losing the whole disk.

To clarify this issue: the DOS FORMAT _is_ destructive on FLOPPY disks.  If
you've formatted a floppy, you can kiss your data good-bye.  In fact, Mace's
Guide even has a section entitled "Recovery of Data from a Formatted Floppy".
It says, basically, "Sorry, you're out of luck.  But you can take the time
now to replace DOS' FORMAT program with my own FORMAT-F program, so that this
problem won't ever happen again."  Mace provides a non-destructive FORMAT-F
for floppy disks.

IBM PC-DOS and Microsoft MS-DOS FORMAT is, as of version 2.x to 3.x,
non-destructive on HARD disks.  Certain vendors who distribute their own
versions of DOS do have FORMATs that are destructive on hard disks, too, but
they are in the minority.

Eric Wang
wang@cs.uiuc.edu