[ale] possible to use hard drives that have bad blocks ?

Greg Freemyer greg.freemyer at gmail.com
Mon Jun 27 12:08:44 EDT 2005


On 6/27/05, Courtney Thomas wrote:
> Thanks Greg.
> 
> This is all new to me and quite interesting.
> 
> I took the first drive that had [at least] one bad block, and did a:
> 
> dd if=/dev/zero of=/dev/hdX
> 
> and then:
> 
> dd if=/dev/hdX of=/dev/null
> 
> and now see NO errors, whereas previous to this write I got an error.
> 
> Does that mean that the drive is now....all right ?
> 
> Cordially,
> Courtney
> 

Obviously you no longer have any data on the drive, but if the second
dd is no longer reporting errors, I would put the drive back in
service without a second thought.

Note: I would get a Sharpie and write directly on the drive the date
and what you did.  That way if six months from now you start seeing
bad blocks again, you will know some of the history of the drive.  If
you still have the LBA of the bad sector, write that on the drive as
well.  ie. Sometimes a sector is marginal and will hold the magnetic
field for months, but not the years that it is supposed to.

Do the other drives you want to salvage have valuable data on them? 
If not, just repeat the above with each of them.

If so, the more surgical approach of using dd with the seek option to
write a single sector is a better approach.

Greg
-- 
Greg Freemyer
The Norcross Group
Forensics for the 21st Century



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