sector hard errors

[Roger Heflin]

Unless you have the drive under raid that means that 15 sectors cannot
be read and you have lost at least some data.

The drives normally will not move sectors that it cannot successfully read.

You may be able to copy the data off the disk, but you may when trying
this find a lot more bad sectors that the 15 that are currently
pending so may find your lost more data than 15 bad sectors would
indicate.

If under mdadm raid then the raid sees the bad sector error and will
reconstruct and write the data back causing the disk to move it.

For the future my only suggestion is either to use raid and/or force
the reading of the disk at least weekly so that the disk will detect
"weak" sectors and either rewrite them or move them as needed.   On
all of my critical disks I read and/or smartctl -t long all disks at
least weekly.   From playing with a disk that is going bad it appears
that doing the -t long daily might keep ahead of sectors going bad,
but that means that the test runs the disk (though it can be accessed
for normal usage) for several hours a day each day.

On Thu, Mar 12, 2015 at 4:40 PM, jd1008 <jd1008 at gmail.com> wrote:
>
>
> On 03/12/2015 03:33 PM, Robert Nichols wrote:
>>
>> On 03/12/2015 04:03 PM, jd1008 wrote:
>>>
>>> --
>>>
>>> On 03/12/2015 01:37 PM, Roger Heflin wrote:
>>>>
>>>> smartctl --all /dev/sd
>>>
>>>
>>> ID#  ATTRIBUTE_NAME          FLAG    VALUE WORST THRESH TYPE UPDATED
>>> WHEN_FAILED RAW_VALUE
>>> 5   Reallocated_Sector_Ct   0x0033   200   200   140 Pre-fail
>>> Always       -       0
>>> 196 Reallocated_Event_Count 0x0032   200   200   000 Old_age
>>> Always       -       0
>>
>>
>> You omitted an important parameter, 197 Current_Pending_Sector. The
>> drive cannot reallocate on a read error.  Reallocation has to wait
>> until the sector is next written.  The sector will remain in the
>> "Pending" state until that occurs.
>>
> 197 Current_Pending_Sector  0x0032   200   200   000    Old_age Always
> -       15
>
> is that bad or not so bad?
>
> --
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