🚀 go-pugleaf

Tom Wheeley <tomw@tsys.demon.co.uk> writes:

>Disk /dev/hda: 32 heads, 63 sectors, 1242 cylinders
>Units = cylinders of 2016 * 512 bytes

>   Device Boot  Begin   Start     End  Blocks   Id  System
>/dev/hda1   *       1       1     520  524128+   6  DOS 16-bit >=32M
>Partition 1 does not end on cylinder boundary:
>     phys=(259, 63, 63) should be (259, 31, 63)
>/dev/hda2         261     261    1023  769104    5  Extended
>/dev/hda5   ?  485753  486691 1405931926593808   6c  Unknown

>Presumably the partition table became corrupted at some point.
>(AFAICR, the cylinder boundary warning appeared before)

(Warning: I don't run linux, so I may be misinterpreting the messages
you quote here...)

If the error message has been appearing and you've been ignoring it,
I would suspect that the extents of hda1 and hda2 are overlapping.  If
this has happened, at some point your system will write to what it
thinks are sectors it owns at the far end of the disk, but in reality
those sectors are part of the partition table chain, plus the FAT,
boot sector, and root directory of the next partition plus some amount
of the data storage space for that partition.

Obviously there are other possible causes for your situation but this
is consistent with what you've posted.

Look at the master partition table, the hd1a boot sector, and the FAT
in hd1a to determine if all allocation data in them are consistent.  I
suspect that it won't be.

Depending on how much has been overwritten, how much you know about
the contents of the D: disk, and how contiguous the files there are (were)
you may or may not be able to recover the data there.  I've done it
in the past, but only because the overwritten partition had just
been defragged with full reorganization, and I had a full listing
of the entire directory tree structure from which I could manually
rebuild the FAT, root, and second-level directory records.

If you're lucky you may find that FAT2 is still present and undamaged
and can be used to rebuild the file system on hda2.  If not you're
probably hosed.


>Is there any way to restore these DOS drives?  I have back-ups or can get hold
>of *most* of the stuff on the drives, but there is a lot of precious data and
>source code there.  (I only installed Win95 a week or two ago, and had not got
>a proper backup system implemented).  I do understand that I could wipe the
>extended partition and start again, but I'd prefer not to!

Start by backing up (after booting from a floppy!) everything on hd1a. 
If it contains files that occupy space also owned by hda2 then fixing
hda2 will overwrite parts of these files.


If you aren't comfortable working with a sector editor and playing with
the bits and bytes of the FAT control tables, you should probably get
help, either from a commercial data-recovery company or from someone 
who you trust to be careful.  Local user groups are a resource you should
consider; they will often have some experts who are willing to help other
users and *may* be better than the commercial outfits.

Joe Morris / MITRE