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[sindi keesan <keesan AT sdf.lonestar.org>]

I went ahead and wrote zeros over the first 512 bytes and then I could 
boot from floppy disk instead of just hard drive.  (I had to first 
keep hitting the space bar while booting in order to boot into linux 
from 2-floppy BL2).

Then PQMagic told me "Disk Manager detected but not running.  Can't 
initialize the engine".  So I zeroed 1024 bytes with BL2 dd.

I then tried BL2 fdisk on it 'Fatal error - bad signature on partition 
table'.


I booted with FreeDOS and was told during boot 'illegal partition table'.
fdisk - First hard disk sector zero has no boot sector ID.
Intialize disk?   Yes.
I made a DOS partition.  FreeDOS fdisk found only 503MB now that I had no 
DDO to make it 1.9G.  I deleted that partition.


Then I dug out the Maxtor diagnostic disk I had downloaded and made and 
ran powermax.exe (it is a boot disk with Caldera DR-DOS).  I did a quick 
low-level format and it zeroed the first 300MB and last 100MB.

I ran their quick 90-sec test and it took at least 10 minutes and told me 
the disk was failing and to back up all my data.  TEST FAILED

Spinrite got normal access speeds, unlike a very slow disk someone once 
gave us that was really failing.

PQMagic again found one 503MB disk with 510 cylinders. (BL2 fdisk had 
found 1946 cylinders, or 1.9GB).

Then I ran BL3 fdisk and it told me that there were 1946 cylinders and old 
versions of LILO and OS/2 and DOS fdisk could only handle 1024 and would 
get confused, and there was also an Invalid flag 0x0000 of partition table 
4 which will be corrected by write.  I wrote and deleted partition 1 in 
DOS format.   Linux detected this drive as 1.9G.  I then made a 200MB and 
a 1.7GB linux partition and wrote the partition table.

FreeDOS booted without any complaint about the partition table this time.

PQMagic again found one 503MB disk, with two linux partitions on it 
totalling 1.9GB.

powermax again told me the disk was failing.  I have not yet run the 
burnin test (we will go away and let it run).  But I may use this as a 
linux disk rather than a 503MB DOS disk, after also doing a more thorough 
check with spinrite.

Perhaps with the correct software I could have removed the DDO and had 
something 1.9G in DOS, but I suspect they made the drive so that is not 
possible.

What might zeroing the first 300MB and the last 100MB have done which
zeroing only the first 1024 bytes did not do, which made this drive usable 
with BL3 fdisk?  Was part of the DDO at the end not the start of the 
drive?


On Fri, 13 May 2005, David Moberg wrote:

> ----- Original Message -----
> From: "sindi keesan" <keesan AT sdf.lonestar.org>
>
> > Can I somehow wipe out this monster with dd from BL instead?  Where
> > might the DDO be located and can I just write zeros over that part?
> >   Is the MBR the first 1024 bytes, or half that?  Could I damage
> > anything important, irretrievably, by trying dd if=/dev/zero
> > of=/dev/hda bs=1024 count=1?
>
> Could you back up everything and wipe the whole disk instead? Writing
> to the MBR is almost guaranteed to destroy any partitioning that you
> may have on there.
>
> David
>
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keesan AT sdf.lonestar.org
SDF Public Access UNIX System - http://sdf.lonestar.org