Bad sectors: how bad can it be

David N davidn04 at
Wed Oct 28 22:31:25 UTC 2009

2009/10/29 Michaël Grünewald <michaelgrunewald at>:
> Hello David,
> thank you for your comments,
> David N wrote:
>> 2009/10/29 Michaël Grünewald <michaelgrunewald at>:
>>> SMART Self-test log structure revision number 1
>>> Num  Test_Description    Status                  Remaining
>>> LifeTime(hours)
>>>  LBA_of_first_error
>>> # 1  Extended offline    Completed without error       00%       458
>>> -
>>> # 2  Extended offline    Aborted by host               70%       456
> [...]
>> If your smartctl says it has used up a spare block
>> (Reallocated_Sector_Ct), replace the drive ASAP. The drives will tend
>> to get more and more bad blocks after the the first one is found,
>> usually because the head is damaging the disks or the head itself is
>> damaged, or other reasons. If its under warranty they usually replace
>> is, talk to the manufacturer before hand.
> I have Reallocated_Sector_Ct=0 for the faulty drive. Where can I find a key
> fo reading all the other exciting numbers listed under the banner
> ``SMART Attributes Data Structure revision number: 10
>  Vendor Specific SMART Attributes with Thresholds:'' ?
> On the hard-drive I use for my backups, a SAMSUNG HD501LJ,  all the numbers
> I read looks fine to me, but I want to be sure. Thus it would be nice have a
> key for the table that `smartctl -a /dev/ad6' outputs. My two other drives,
> I use to store my OS and my data, are MAXTOR STM3250820AS (I do not have a
> RAID setup, it just happens that I have twin hard drives). They both have
> `Reallocated_Sector_Ct=0' but have positive `Raw_Read_Error_Rate',
> `Seek_Error_Rate'. Additionally, the faulty drive has positive
> `Reported_incorrect=119',`Current_Pending_Sector=4294967295' and
> `Offline_Uncorrectable=4294967295'.
> As looking for hints on google leads to many threads discussing hard-drive
> failures, I did not find what a pleasant description of the signification of
> these numbers.
> --
> Kind regards,
> Michaël

More information

> `Seek_Error_Rate'. Additionally, the faulty drive has positive
> `Reported_incorrect=119',`Current_Pending_Sector=4294967295' and
> `Offline_Uncorrectable=4294967295'.

It looks like your drive is trying to remap a bad block, but can't
seem to do so. You may need to do a cold boot. Or force a read/write
from that sector to tell the drive to try to remap it again.
dd if=/dev/adX of=/dev/null skip=4294967295 count=1 (Read from the block#)

Looks like your HDD with the positive Current_Pending_Sector and
Offline_Uncorrectable with that is going bad. Once it manages to remap
the block, your Reallocated_Sector_Ct will increase/decrease (depends
on the counter), once it reaches the THRESH counter, its out of blocks
to map.

I would recommend you change HDD as soon as possible.

David N

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