How to fix Current_Pending_Sector?

[Iain Rauch <groups@email.iain.rauch.co.uk>]

Smartd emailed me to say I have "1 Currently unreadable (pending) sectors".
This actually happened for two disks now.

I ran a check and then a repair on my array and they both gave mismatch_cnt
of 8.

I ran a long self-test on both and they completed without error with no
errors logged. Yet the 'Current_Pending_Sector' is still 1 on both, and one
disk also has a 'UDMA_CRC_Error_Count' of 1.

I ran 'hdrecover' on both and they are both telling me "Couldn't recover
sector 2930277168". It's asking if I want to overwrite it with zeros to fix
it, but I would assume this will damage my array?

The disk sizes are 1500301910016 bytes and I use 1500250M partition sizes
for the array components. Does that sector fall outside my partition, and
hence would it be safe to overwrite it with zeros?

Also, why did I have a mismatch_cnt? I haven't run another check since I did
the repair, as I wanted to fix the pending sector.

BTW, I have a 15 drive RAID6.

Hope y'all can help.


Iain