[smartmontools-support] Extended test doesn't catch CurrentPendingSector and OfflineUncorrectableSector errors

[Christian Franke]

Dipanjan Das wrote:
>
>     After such a read scan, some of the bad LBAs should appear in the
>     "SMART
>     (Extended Comprehensive) Error Log."
>
>
> How do I print out this "Extended Comprehensive" error log? Is it the 
> same '-x' switch you are referring to?

'smartctl -l xerror', included in 'smartctl -x'.


> ...
> I ran ''ddrescue" on the whole disk. But, the result is confusing. The 
> "read errors" field contains 1, but the generated map file doesn't 
> contain any bad sectors (status column with '-' character). I am 
> including both the ddrescue output, the map file, and the relevant 
> part from the 'smartctl -x' output so that someone can shed some 
> light. I am specifically curious to find out 1 Current_Pending_Sector, 
> 6 Offline_Uncorrectable, and the LBA(s) marked by the extended 
> self-test. Also, I am not being able to add up why ddrescue reports 
> one read error, but that is not reflected in the map file. I expected 
> the read error to match with the LBA_of_first_error field of smartctl 
> self-test.
>
> =============
> ddrescue output
> =============
> # ddrescue --ask --verbose --binary-prefixes --idirect --force 
> /dev/sdc /dev/null disk.map
> GNU ddrescue 1.22
> About to copy 1863 GiBytes
> from '/dev/sdc' [UNKNOWN] (2000398934016)
>   to '/dev/null' (0)
> Proceed (y/N)? y
>     Starting positions: infile = 0 B,  outfile = 0 B
>     Copy block size: 128 sectors       Initial skip size: 39168 sectors
> Sector size: 512 Bytes
>
>      ipos:   1852 GiB, non-trimmed:        0 B,  current rate:   22528 B/s
>      opos:   1852 GiB, non-scraped:        0 B,  average rate: 79108 KiB/s
> non-tried:        0 B,  bad-sector:        0 B,    error rate:       0 B/s
>   rescued:   1863 GiB,   bad areas:        0,        run time:  6h 51m 33s
> pct rescued:  100.00%, read errors:        1,  remaining time:         n/a
>                               time since last successful read:         n/a
> Finished
>
>
> ============
> ddrescue map
> ============
> # cat disk.map
> # Mapfile. Created by GNU ddrescue version 1.22
> # Command line: ddrescue --ask --verbose --binary-prefixes --idirect 
> --force /dev/sdc /dev/null disk.map
> # Start time:   2021-07-11 15:40:45
> # Current time: 2021-07-11 22:32:18
> # Finished
> # current_pos  current_status  current_pass
> 0x1CF0266FE00     +               1
> #      pos        size  status
> 0x00000000  0x1D1C1116000  +
>

Ddrescue may perform various passes, see 'info --node Algorithm 
ddrescue' for details.

This ddrescue result suggests that there was a read error in the first 
pass which disappeared in a later pass.


> ============
> smartctl -x
> ============
> SMART Attributes Data Structure revision number: 16
> Vendor Specific SMART Attributes with Thresholds:
> ...
> SMART Extended Self-test Log Version: 1 (1 sectors)
> Num  Test_Description    Status                  Remaining 
>  LifeTime(hours)  LBA_of_first_error
> # 1  Selective offline   Completed: read failure       90% 54367       
>   3884004178
> # 2  Selective offline   Completed without error       00% 54367         -
> # 3  Selective offline   Completed: read failure       70% 54367       
>   3884004178
> # 4  Selective offline   Completed: read failure       90% 54367       
>   3884004178
> # 5  Extended offline    Aborted by host               70% 54367         -
> # 6  Extended offline    Completed: read failure       90% 54268       
>   3884004178
> # 7  Extended offline    Completed without error       00% 54206         -
> # 8  Extended offline    Completed without error       00% 54199         -
> # 9  Extended offline    Completed: read failure       90% 54190       
>   3884004178
> #10  Short offline       Completed without error       00% 54189         -
> #11  Extended offline    Completed without error       00% 53801         -
> #12  Short captive       Completed without error       00%  1530         -
> 1 of 5 failed self-tests are outdated by newer successful extended 
> offline self-test # 7
>

This log matches the ddrescue result. Read of (at least) LBA 3884004178 
failed occasionally and worked again in later tests. Unfortunately the 
disk firmware did not redirect this weak sector.


> SMART Selective self-test log data structure revision number 1
> ...
>


This isn't a full '-x' output. "SMART Extended Comprehensive Error Log" 
and other items are missing.

Please redirect smartctl output to a file and post it as an plaintext 
attachment. Add '-q noserial' if desired.

Thanks,
Christian