Bad sectors: how bad can it be

Matthew Seaman m.seaman at
Tue Oct 27 08:16:21 UTC 2009

Grünewald Michaël wrote:
> Dear list,
> after an incorrect power-off of my FreeBSD system, it does not boot any 
> more, BTX stops even before showing the cute beastie menu. Starting the 
> machine by other means, I found that the hard-drive is installed on has 
> bad sectors. I am looking for advices on how to recover from this, if 
> possible.
> Basically the question is: shall I discard my hard-drive with 
> bad-sectors, or can I continue using it?
> The Linux system I use to diagnose this says:
>   hdb: media error (bad sector): status=0x51 { DriveReady SeekComplete 
> Error }
>   hdb: media error (bad sector): error=0x30 { LastFailedSense=0x03 }
>   ...
>   Buffer I/O error on device hdb, logical block 1663200
> etc.
> Since I use computers (1992) these are my first bad sectors :) (on hard 
> drives, taking floppies into account is no fun!). I hence have several 
> questions:
>   -- is it possible to let these sectors?
>   -- to which extents a hard-drive with bad sectors is usable?
>   -- while the apparition of these bad sectors coincide with an 
> incorrect power-off, are the two events related? The machine suffered 
> plenty improper power-offs (or many), in the last years and did not 
> react so badly!

Yes.  Back up your data and replace that disk ASAP.  It's toast.

All disks come with a built-in set of spare sectors, which the firmware
will automatically substitute for any sectors that go bad.  If you get
to the state where the OS is seeing bad blocks, it means the disk has
run out of spare sectors.  It's worn out.



Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
                                                  Flat 3
PGP:     Ramsgate
                                                  Kent, CT11 9PW

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