Can't I get a /dev/one?

James Wilkinson james at westexe.demon.co.uk
Wed Jul 14 12:06:58 UTC 2004


William M. Quarles is having problems with a hard disk drive.

Mike Fedyk suggested:
> Yeah, just run badblocks -w on the drive and be done with it... ;)

William replied: 
> Good guess!
> 
> Well, that's an idea.  And I'm trying it.  It's yet to tell me anything 
> bad, though, which all of the DOS-mode Windows programs have complained 
> about bad sectors already (it does produce output upon each error, 
> doesn't it?).  I'm a physicist and I believe that their should be a way 
> to coax bad blocks out of being bad.  However, I'm not sure that 
> badblocks is writing the patterns in a way that is conducive to the 
> coaxing.  Actually, I know one reason that it may not be conducive is if 
> it fails to write and read with one number pattern on a block, it would 
> note that block as being bad and go on to the next: however, my coaxing 
> theory would require all of the patterns to be written to the disk, and 
> in an order that causes all of the bits to be flipped frequently.  There 
> is also a federal procedure for the binary code that is to be written to 
> a drive to make sure that it old data is wiped clean, I need to look 
> that up and try it.

You might not be aware of this:

Modern hard disk drives keep a number of sectors spare. When a sector
fails (or is failing), and the computer attempts to write to that sector,
the hard drive will automatically use one of its spare sectors instead.
Any further references to that sector will automatically be rerouted to
the new, good location.

This is all done internally by the drive: the OS typically never even
sees this.

It sounds like you've already written zeros to the entire drive. This
would have replaced all the bad blocks already: you *shouldn't* see any
bad blocks.

If you do, then the disk has used up all its spare sectors and is dying.
Don't use it for any data you can't easily recreate.

HTH,

James.
-- 
E-mail address: james@ |    "Drink", said the Irish preacher, "is the curse
westexe.demon.co.uk    | of the country. It makes ye quarrel with yer
                       | neighbours, it makes ye shoot at yer Landlord, and
                       | it makes ye miss him."





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