SMART error each hour for a SSD, due to "unreadable (pending) sectors"

[Omer Zak]

I have a laptop with a 1TB SSD.
The smartd daemon logs an error each hour as follows:
-=-=-=->
Device: /dev/sda [SAT], 1 Currently unreadable (pending) sectors

Device info:
CT1000MX500SSD4, S/N:2027E2B39329, WWN:5-00a075-1e2b39329, FW:M3CR023,
1.00 TB

For details see host's SYSLOG.
-=-=-=->

When I run: sudo smartctl /dev/sda -a
I get a lot of information which I do not understand its implications.
However, the device has SMART capability but it is not in smartctl
database and:
-=-=-=->
SMART overall-health self-assessment test result: PASSED
-=-=-=->

When I run: sudo egrep /dev/sda /var/log/syslog
I get:
-=-=-=->
May  4 00:02:36 c5 smartd[1014]: Device: /dev/sda [SAT], No more
currently unreadable (pending) sectors, warning condition reset after 1
email
May  4 00:02:36 c5 smartd[1014]: Device: /dev/sda [SAT], SMART Usage Attribute: 194 Temperature_Celsius changed from 56 to 62
May  4 00:32:36 c5 smartd[1014]: Device: /dev/sda [SAT], 1 Currently unreadable (pending) sectors
May  4 00:32:36 c5 smartd[1014]: Device: /dev/sda [SAT], SMART Usage Attribute: 194 Temperature_Celsius changed from 62 to 59
May  4 01:02:36 c5 smartd[1014]: Device: /dev/sda [SAT], No more Currently unreadable (pending) sectors, warning condition reset after 1 email
May  4 01:02:36 c5 smartd[1014]: Device: /dev/sda [SAT], SMART Usage Attribute: 194 Temperature_Celsius changed from 59 to 64
May  4 01:32:37 c5 smartd[1014]: Device: /dev/sda [SAT], 1 Currently unreadable (pending) sectors
May  4 01:32:37 c5 smartd[1014]: Device: /dev/sda [SAT], SMART Usage Attribute: 194 Temperature_Celsius changed from 64 to 59
-=-=-=->
and the above repeats each hour.

The laptop seems to work OK with no data loss or such.
However I'd like to understand what is going on and if possible how to
get rid of the warnings.

One more fact which may have bearing: few months ago, had the laptop's
256GB SSD replaced by a 1TB SSD.

Any suggestions how can I troubleshoot it?
Any additional information I should look at?

Thanks,
--- Omer Zak



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