Path: utzoo!attcan!uunet!husc6!mailrus!uflorida!gatech!udel!mmdf
From: gay%elde.epfl.ch@cunyvm.cuny.edu (David Gay)
Newsgroups: comp.sys.amiga
Subject: Re: Disk-Validator failure
Message-ID: <6214@louie.udel.EDU>
Date: 4 Jan 89 11:36:53 GMT
Sender: mmdf@udel.EDU
Lines: 62

In article <304@ibmpa.UUCP> saare@ibmpa.uucp (John Saare) writes:
>
>This is the problem:

[description removed]

>As a file is being written, a Volume R/W error requestor appears and I select
>"cancel".  Using "protect", I quarantine the directory the error occurred in
>and cross my fingers.  I use the system for a while THEN, ON ANOTHER DAY:
>The machine crashes, for reasons related to my being 2Mb short.  The machine
>reboots, and..., Disk-Validator has a go at the disk.  Because the bad block
>is allocated, Disk-Validator tries to read it, and fails. So, given:
>    - If I'd wanted a 70Mb R/O drive, I would have bought a CD-ROM.
>    - I WILL NOT RE-FORMAT THE DRIVE !!! (ahem, didn't mean to shout...)
>    - I'm willing to live with occasional bad sectors if AmigaDOS
>      will let me...
>How can I get back a validated disk?  Can a "diskdoctor"ed
>file system be used normally, or is re-formatting mandatory?  Are there
>any utilities, commercial($$$) or PD($) that will remove specified/bad blocks
>from the FFS free pool (is there such a thing in FFS?)?

The problem is that the validator will rebuild this "pool" (the bitmap),
hence one has to rerun such a program after every validation session (very
annoying). My hard disk came with such a program to map out bad blocks (in
the bitmap). However this has two disadvantages 1) see above, 2) Format fails
on the bad blocks ...  (You can get round this, but it is even more annoying).
I got so frustrated that I wrote myself a bad block mapper which replaces
all references to bad blocks with a block taken from a track that I reserved
(0, but could be any really).

I can send you this program (though it's still in a rather hacked state:
it could use less memory, it never exits, it doesn't do much checking ...),
however you said you didn't want to reformat your hard disk (Just one
advantage, once you've setup the bad block map (reserved a track), you can
map out extra bad blocks w/o reformatting the disk).

There is also a commercial program that reserves bad blocks, that comes with
the Disk Mechanic. A friend of mine has it, but he tells me he's never got it
to work ... (It crashes halfway through apparently).

Finally, you could fool around with a disk editor and put the bad block in
a special file that you will never read (you can always set the protection
bits). I guess it's currently marked as belonging to a file header, directory,
... seeing that the validator tries to read it.

>
>And now in an act of utter desperation...
>If somebody can ACCURATELY solve my problem, I'll promise to be a
>better person and/or Usenet citizen.  I'll contribute more often, or
>at all, even.  I'll participate in the discussions, but not fan the flames.
>
>Thank you -- John Saare

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
David Gay                       Another mad amigan
GAY@ELDE.EPFL.CH, or GAY%ELDE.EPFL.CH@CEARN.bitnet

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

P.S. A "techish" question: which io_Commands must a filing system device
provide ? My program traps CMD_READ, CMD_WRITE and TD_FORMAT. Is that
sufficient ?