MS Disk Occupation System strikes again

MS Disk Occupation System strikes again

Post by Brett Gersekows » Wed, 30 Aug 1995 04:00:00



[ Article crossposted from aus.computers.linux ]
[ Author was Brett Gersekowski ]
[ Posted on 29 Aug 1995 21:41:15 GMT ]

MS-DOS (or was it MS-LOSS) SUX!!

I'm doing a bit of rearranging on my system. I had a heap of important
information "backed up" on an ext2 filesystem on my second hdd.

Cutting to the chase, MS-DOS's fdisk trashed my partition table. It went
fine on my first drive, but on the second drive it wouldn't let me do
anything, and when I went back to Linux, the partition table on the
second drive was screwed.

I find myself thinking this way, though. Only the Partition table has
been screwed, right??
Therefore, if I could rebuild the entry for that partition on the drive's
partition table, everything should be OK??
I know roughly where the partition started, and I know EXACTLY where it
ended (cos it was the end of the disk).
I'm not sure how the ext2 filesystem is set out, but could I use the
special file /dev/hdb to read and search for the superblock of this
partition. How would I identify this partition?? Is the superblock offset
at all from the start of the partition??
Assuming I can and have gotten as far as locating the EXACT start of the
ex-partition, would simply using fdisk and telling it to create a new
partition with these cylinder numbers as start and end reincarnate my
beloved data??

Finally, I guess, has anybody ever run into this before and know of a
utility that may be able to help me with this??

Any comments would be great. Most of that stuff is replaceable (ignoring
the amount of time it will take to actually replace it), but some stuff
that was rather important isn't replaceable, and is in limbo at the
moment and I really want to get it back...

Thanks in advance...

Brett :)

 
 
 

MS Disk Occupation System strikes again

Post by Johannes Stil » Thu, 31 Aug 1995 04:00:00




[...]

Quote:>Cutting to the chase, MS-DOS's fdisk trashed my partition table. It went
>fine on my first drive, but on the second drive it wouldn't let me do
>anything, and when I went back to Linux, the partition table on the
>second drive was screwed.

>I find myself thinking this way, though. Only the Partition table has
>been screwed, right??

Who knows?

Quote:>Therefore, if I could rebuild the entry for that partition on the drive's
>partition table, everything should be OK??

Yes.

Quote:>I know roughly where the partition started, and I know EXACTLY where it
>ended (cos it was the end of the disk).
>I'm not sure how the ext2 filesystem is set out, but could I use the
>special file /dev/hdb to read and search for the superblock of this
>partition. How would I identify this partition?? Is the superblock offset
>at all from the start of the partition??

The superblock is offset 1 block (1024 bytes or 2 sectors) from the
start of the partition because the first block is reserved for a boot
loader.

You can find superblocks with the command

od -x /dev/hdb | grep ef53

You should get a output line like:

0002060 7450 3044 0008 0014 ef53 0000 0001 0000
    ^^^                     ^^^^

You will get many of these lines. Throw away all of them that don't
have the first number ending with "060" and that don't have the "ef53"
in the same position.

The first number is the disk position of this piece of data as octal
value. Subtract 02060 (octal) (=1072 dec.) to get the absolute start of
the possible partition. If it is the right position, the pattern quoted
above should repeat every 8MB (40000000 octal).

Check whether this possible partition start makes sense, e.g. typically
it should be on a cylinder boundary.

Be very careful with extended partitions, as the subpartitions inside
an extended partition have a sub-partition table in front of them (and
start at the next sector, block or even the next track).

Best bet is to just use Linux fdisk to put a primary partition at the
location where you think the partition was. This should work even it
was originally a logical partition inside an extended partition.

It does not matter if you make the partition bigger that the original
one was (hardly possible in your case).

Quote:>Assuming I can and have gotten as far as locating the EXACT start of the
>ex-partition, would simply using fdisk and telling it to create a new
>partition with these cylinder numbers as start and end reincarnate my
>beloved data??

Yes, provided the data area itself has not been overwritten. But DON'T
use DOS fdisk, it has an inclination to overwrite the start of a newly
created partition just to make it invalid.

[...]

        Johannes

 
 
 

1. MS strikes again...

From the Daily Texan (campus paper for the University of Texas at
Austin) http://stumedia.tsp.utexas.edu/webtexan/today/ -- though I
suppose the "today" part will roll over pretty soon.  Click the link in
the right-hand sidebar.

Elipses indicates snips, mostly very short.  Brackets are mine:

---8<------

"Microsoft, UT make deal

     Elizabeth Jessop
     Daily Texan Staff

     The UT System announced an agreement with Microsoft Wednesday that
will
     allow UT students, faculty and staff to get a battery of Microsoft
software at a sizable
     discount.
...
     Under the new deal, students could purchase a package of programs
including
     Microsoft Word, Excel, Powerpoint and Outlook for $5.
...
    The agreement will cost the UT System $6.3 million, said Goldsmith,
who helped to
     engineer the deal.

     He said the money is well spent because it will make all the
computers throughout
     the system compatible with each other.
...
     Although the deal won't bind the UT System into using only
Microsoft products in
     their computers, UT officials said they hoped the new inexpensive
software would
     help link up many of the computers across the UT System's 15
campuses.
...
    "Microsoft is committed to the higher education community," she said
in a prepared
     statement. "Colleges and universities are grappling with the issue
of software
     standardization, so we are working out custom agreements with
institutions, like
     the University of Texas System."   [That "she" is a MS marketing
manager.]

     Students, faculty and staff with no computer at home would also
stand to benefit
     from the agreement, UT officials said, because Microsoft products
have been
     installed in all campus computers.   [Sequitur?]
...
     Mario Gonzalez, vice chancellor for telecommunications and
information
     technology for the UT System, said this could be the start of a
"serious commitment"
     to Microsoft.   [Oh-oh!]
...
The contract will expire after four years, on Aug. 31, 2002."

---8<------

Bobby Bryant
Austin, Texas

2. Software track......

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