Bad sectors: how bad can it be

Jerry gesbbb at
Tue Oct 27 09:23:38 UTC 2009

On Tue, 27 Oct 2009 08:16:07 +0000
Matthew Seaman <m.seaman at> replied:

>Gr_newald Micha_l 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.

A friend of mine had a lap-top that exhibited similar behavior. After
trying the usual methods, he used SpinRite
<> at its highest level on the disk. It
ran for 97 hours; however, when completed, the disk worked like new.

While replacing the drive is certainly a good idea, if you need
information on it that you cannot otherwise extract, you might want to
try another method.

gesbbb at


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