[smartmontools-support] Extended test doesn't catch CurrentPendingSector and OfflineUncorrectableSector errors
Christian Franke
Christian.Franke at t-online.de
Sun Jul 11 18:27:47 CEST 2021
Claudio Kuenzler wrote:
>
> With "smartctl -a /dev/mydevice", I can only see this information:
>
> ==========================
> 197 Current_Pending_Sector 0x0032 200 200 000 Old_age
> Always - 1
> 198 Offline_Uncorrectable 0x0030 200 200 000 Old_age
> Offline - 6
> ==========================
>
> Is there any way to know which exact sectors are affected?
>
>
> Not with smartmontools, to my current knowledge.
Some recent drives support the "Pending Defects log". Try 'smartctl -l
defects'. This is included in 'smartctl -x' but not in '-a'.
> But you could use "dd" or some other disk tools/commands. dd should
> output when a read error occurs and should also print the sector(s).
> Look at the manpage and use "noerror".
After such a read scan, some of the bad LBAs should appear in the "SMART
(Extended Comprehensive) Error Log."
Note: Use 'smartctl -x' because '-a' only prints legacy SMART logs which
only support 28-bit LBAs.
I often use GNU ddrescue (https://www.gnu.org/software/ddrescue/) for
read scans. It writes a map file of good/bad/non-tried byte ranges. This
allows to interrupt the scan at any time and resume it later. There is
also an option to limit the read rate.
See the Bad Blocks HOWTO for a real world use case:
https://www.smartmontools.org/wiki/BadBlockHowto#RecoveringamostlyunreadablesectorofaNotebookHDD
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