Tape dumping programs for Unix/Linux... 8-inch disks with bad blocks.

From: Raymond Moyers <rmoyers_at_nop.org>
Date: Thu May 2 21:24:58 2002

On Thursday 02 May 2002 18:54, you wrote:

> I have many 8-inch disks with bad blocks. I'd like to preserve
> the data if at all possible. A simplistic 'dd'-style read
> won't preserve everything; it'll bail out when it has a problem.

 In dos you could do that with a batfile script of looping debug
 commands

 ie read sector > mem write sector mem > another disk

 when you are done with a floppy you would have
 all the readable sectors on a new floppy or whatever
 with the bad ones left containing whatever bits
 it could get if any along with the prev sectors data

 You could at least spool the new disk to a file and
 worry over the missing bits..

 Ive done this before with bad PC floppies that
 could not be mounted in any way, ie trashed
 unreadble block 0, alien file system etc.

 I suppose you could hack fdformat ( the verify code etc )
 into a very respectable floppy recovery tool that would give
 you all the good sectors to a file with the nonreadble sectors
 filled with zeros..

 one scheme perhaps .. have your set of "tools"
 write a empty recovery file preinit with zeroed blocks
 (easy to do with dd)
 and then write only good reads into their respective
 positions, that way in the attempt to get a good read
 of bad sectors .. bad reads of once good sectors
 wont trash good data you managed to get already

 Hey .. its an idea. there is lots of "getsector" code out
 there burried in a lot of things that you could wrap
 your own code around .. you might not even wrap
 it with much ...

The following is only a simulation

 #getsector --help
 Usage: getsector -d device -s relative_sector

 fill in the rest with shell scripting ... wouldnt be fast
 but simple brute force is often better

 Isnt there a readtrack command on some controllers ?

 You could come at this from a few angles i suppose.

 Raymond
Received on Thu May 02 2002 - 21:24:58 BST