"LifeTime(hours)" wrap around in SMART's self-test log

[C_Aulbert]

Hi

I've just seen that on a few quite old disks, the 16bit counter for "LifeTime(hours)" wraps around after a few years, even though the power on hours don't.

I'm not sure if this is caused the SMART specs or a problem with querying the raw values within smartmontools, but it would be nice to have a fix in smartmontools to have a uniformly growing number of LifeTime in the logs - especially as we use the difference between the latest entry and attribute no 9 to determine if a regular check was not performed.

What do you think?

Cheers

Carsten

smartctl 6.5 2016-04-02 r4276 [x86_64-linux-3.18.26-atlas] (daily-20160402)
Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Hitachi Ultrastar A7K1000
Device Model:     Hitachi HUA721075KLA330
Serial Number:    GTE200P8G1Z07E
LU WWN Device Id: 5 000cca 215c0e504
Firmware Version: GK8OA70M
User Capacity:    750,156,374,016 bytes [750 GB]
Sector Size:      512 bytes logical/physical
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ATA/ATAPI-7 T13/1532D revision 1
Local Time is:    Mon Apr  4 13:07:04 2016 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status:  (0x85) Offline data collection activity
                                        was aborted by an interrupting command from host.
                                        Auto Offline Data Collection: Enabled.
Self-test execution status:      ( 249) Self-test routine in progress...
                                        90% of test remaining.
Total time to complete Offline 
data collection:                (11471) seconds.
Offline data collection
capabilities:                    (0x5b) SMART execute Offline immediate.
                                        Auto Offline data collection on/off support.
                                        Suspend Offline collection upon new
                                        command.
                                        Offline surface scan supported.
                                        Self-test supported.
                                        No Conveyance Self-test supported.
                                        Selective Self-test supported.
SMART capabilities:            (0x0003) Saves SMART data before entering
                                        power-saving mode.
                                        Supports SMART auto save timer.
Error logging capability:        (0x01) Error logging supported.
                                        General Purpose Logging supported.
Short self-test routine 
recommended polling time:        (   1) minutes.
Extended self-test routine
recommended polling time:        ( 191) minutes.
SCT capabilities:              (0x003f) SCT Status supported.
                                        SCT Error Recovery Control supported.
                                        SCT Feature Control supported.
                                        SCT Data Table supported.

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  1 Raw_Read_Error_Rate     0x000b   100   100   016    Pre-fail  Always       -       0
  2 Throughput_Performance  0x0005   130   130   054    Pre-fail  Offline      -       151
  3 Spin_Up_Time            0x0007   118   118   024    Pre-fail  Always       -       542 (Average 472)
  4 Start_Stop_Count        0x0012   100   100   000    Old_age   Always       -       82
  5 Reallocated_Sector_Ct   0x0033   100   100   005    Pre-fail  Always       -       2
  7 Seek_Error_Rate         0x000b   100   100   067    Pre-fail  Always       -       0
  8 Seek_Time_Performance   0x0005   132   132   020    Pre-fail  Offline      -       33
  9 Power_On_Hours          0x0012   091   091   000    Old_age   Always       -       66329
 10 Spin_Retry_Count        0x0013   100   100   060    Pre-fail  Always       -       0
 12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       82
192 Power-Off_Retract_Count 0x0032   100   100   000    Old_age   Always       -       868
193 Load_Cycle_Count        0x0012   100   100   000    Old_age   Always       -       868
194 Temperature_Celsius     0x0002   166   166   000    Old_age   Always       -       36 (Min/Max 8/47)
196 Reallocated_Event_Count 0x0032   100   100   000    Old_age   Always       -       2
197 Current_Pending_Sector  0x0022   100   100   000    Old_age   Always       -       0
198 Offline_Uncorrectable   0x0008   100   100   000    Old_age   Offline      -       0
199 UDMA_CRC_Error_Count    0x000a   200   200   000    Old_age   Always       -       0

SMART Error Log Version: 1
No Errors Logged

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%       676         -
# 2  Extended offline    Completed without error       00%       508         -
# 3  Extended offline    Completed without error       00%       340         -
# 4  Extended offline    Completed without error       00%       172         -
# 5  Extended offline    Completed without error       00%         4         -
# 6  Extended offline    Completed without error       00%     65372         -
# 7  Extended offline    Completed without error       00%     65205         -
# 8  Extended offline    Completed without error       00%     64868         -
# 9  Extended offline    Completed without error       00%     64700         -
#10  Extended offline    Completed without error       00%     64532         -
#11  Extended offline    Completed without error       00%     64484         -
#12  Extended offline    Completed without error       00%     12930         -
#13  Extended offline    Completed without error       00%     12762         -
#14  Extended offline    Completed without error       00%     12594         -
#15  Extended offline    Completed without error       00%     12426         -
#16  Extended offline    Completed without error       00%     12258         -
#17  Extended offline    Completed without error       00%     12090         -
#18  Extended offline    Completed without error       00%     11922         -
#19  Extended offline    Completed without error       00%     11754         -
#20  Extended offline    Completed without error       00%     11586         -
#21  Extended offline    Completed without error       00%     11418         -

SMART Selective self-test log data structure revision number 1
 SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS
    1        0        0  Not_testing
    2        0        0  Not_testing
    3        0        0  Not_testing
    4        0        0  Not_testing
    5        0        0  Not_testing
Selective self-test flags (0x0):
  After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.

[Christian Franke]

Actually the ATA spec is the problem: The Life timestamp field is only 16 bit wide in both variants of the SMART self-test log.

Overflow could only be detected if any old test with up to 65535 hours is still in the log. I'm not sure whether this is worth the effort for rare disks with a power on time of at least ~7.5 years.

I leave the ticket open as 'undecided' for now.

BTW:

smartctl 6.5 2016-04-02 r4276 [x86_64-linux-3.18.26-atlas] (daily-20160402)

Thanks for testing our daily builds :-)

[Alex Samorukov]

I am agree with chrfranke + also want to add that relying on attribute 9 is not an option, because different drives using different format for it + sometime it is just buggy or not working as it should due to fw issues.

[C_Aulbert]

OK, if the ATA specs are too old for such a disk age, I guess you are right. Let's ignore this edge case - although the disks are really good and fine.

If you think it would be a more or less trivial patch to check for the overflow in the logs and account for it, I would very much like that in the output, but I don't really know how much effort that would be or worth it. And I guess I won't be able to persuade Bruce to look into the code again ;)

With respect to the version used: Well, I thought with the system-installed version (5.41, please don't hit me too hard) I would only create a bad initial reputation here, thus I just used the very latest static build you gracefully provided.

[Christian Franke]

This is a limitation of the ATA self-test logs. A possible workaround has only very limited use cases. See comments above for details.

[Christian Franke]

Ticket #1418 has been marked as a duplicate of this ticket.