[smartmontools-support] selt-tests hours record inferior to current power in hours

[Corentin Labbe]

Hello

When doing a self test, I have multiple drive which record it with a lifetime different than current power on hours:
Example 1:
  9 Power_On_Hours          0x0032   089   089   000    Old_age   Always       -       52717
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Short offline       Completed without error       00%      9937         -
# 2  Short offline       Completed without error       00%      9821         -
# 3  Extended offline    Completed without error       00%      9818         -
# 4  Extended offline    Completed without error       00%      9776         -
# 5  Extended offline    Completed without error       00%      7284         -
# 6  Extended offline    Completed without error       00%      7284         -
# 7  Short offline       Completed without error       00%     17463         -
# 8  Extended offline    Completed without error       00%     16958         -
# 9  Extended offline    Completed without error       00%     15021         -
#10  Extended offline    Completed without error       00%     14404         -
#11  Extended offline    Completed without error       00%     14386         -

This driver just got a self test today
As can be seen, the last is at 9937 hours but current Power_On_Hours is 52717.

Example 2:
I got another driver with the same problem:
  9 Power_On_Hours          0x0032   007   007   000    Old_age   Always       -       68178
Num  Test_Description    Status                  Remaining  LifeTime(hours)  LBA_of_first_error
# 1  Short offline       Completed without error       00%      2642         -
# 2  Short offline       Completed without error       00%      2642         -
# 3  Extended offline    Interrupted (host reset)      90%      1346         -
# 4  Extended offline    Interrupted (host reset)      80%      1298         -
# 5  Extended offline    Interrupted (host reset)      10%       483         -
# 6  Extended offline    Completed without error       00%       467         -
# 7  Extended offline    Interrupted (host reset)      50%     61490         -
# 8  Extended offline    Completed without error       00%     60302         -
# 9  Short offline       Completed without error       00%     60299         -
#10  Extended offline    Completed without error       00%     60028         -
#11  Extended offline    Completed without error       00%     58615         -
#12  Short offline       Completed without error       00%     58568         -
#13  Extended offline    Completed without error       00%     52790         -
#14  Extended offline    Completed without error       00%     50530         -
#15  Extended offline    Completed: read failure       90%     50290         105986680
#16  Extended offline    Completed without error       00%     50057         -
#17  Short offline       Completed without error       00%     50054         -

In example 2, the difference is exactly 65536, but example 1 is 42780.

Does this is normal ?

Regards