From: BlueChip <cs_bluechip_at_webtribe.net>
Date: Tue, 20 Apr 2004 09:55:33 +0100

At 07:04 20/04/04, you wrote:
>Glenn Ervin at Home wrote:
>>Why not just do a scandisk and fix the errors?
>
>Scandisk can't fix bad sectors. All it can do is to prevent the file
>system from using them. A new hard disk shouldn't have sector errors in
>the first place.
>
>(Or have I just been lucky to never have seen sector errors at all on any
>of my hard disks? Anyone?)
>
>Linus

Every hard drive has bad sectors.

afaik (and certainly this was true about 2 years ago) it is/was impossible
to manufacture PERFECT drive platters. So what the manufacturers started
doing was under-quoting the size of the HDD so they could "keep some back".

The upshot is that your "100GB" HDD will likely have (and >this> number is
a guess) 110MB of Platter space - this means that the HDD can lose (about)
10% of platter surface, and with some clever hardware, those corrupt
sectors will be remapped to the "reserve" drive space and you (the user)
will never be any the wiser.

This kind of malarky is coupled with technologies such as S.M.A.R.T. drive
management to warn of dying hard drives before it is "too late."

I would suggest that any modern hard drive which is declaring bad sectors,
has already used it's 'reserve area' and any sectors that start to die in
the future will simply appear as bad sectors because there is no
'remapping' room left.

There are bits of software such as SpinRite which can perform recovery on
bad sectors and often a low level format will show some improvement, but
imho if you haev a modern drive which is declaring bad sectors - bin it!

If you do plan to muck around with low level format realise two things:
# Use the low level format tool supplied by the manufacturer which is
targetted for your specific drive (that could also read do NOT use the BIOS
low level format routines)
# If you get power loss during a LLFormat, thrown the drive in the bin - it
is dead

BC

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Received on 2004-04-20