[smartmontools-support] Understanding 'not capable of SMART self-check' and 'failed to read SMART Attribute Data' from smartd?

[Dachshund Digital]

Understanding 'not capable of SMART self-check' and 'failed to read 
SMART Attribute Data' from smartd?

I can execute the -H check which reports PASSED for the drive in 
question.  I can execute the -P show variant of the smartctl command 
sequence.  I can execute the (detail) information variant of the 
smartctl command sequence.  No errors or alerts presented by any of the 
these commands, so I don't understand what smartd is reporting, when the 
results from smartctl show no issues, apparently?  I am new to 
smartmontools... so am I missing something (obvious) here?

# smartctl -i /dev/sdb
smartctl 7.1 2019-12-30 r5022 [armv7l-linux-5.4.72-v7l+] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Western Digital Red
Device Model:     WDC WD40EFRX-68N32N0
Serial Number:    WD-WCC7K3CYK13E
LU WWN Device Id: 5 0014ee 264f48324
Firmware Version: 82.00A82
User Capacity:    4,000,787,030,016 bytes [4.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    5400 rpm
Form Factor:      3.5 inches
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-3 T13/2161-D revision 5
SATA Version is:  SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Mon Nov 16 00:51:09 2020 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

root at pi4modelb1:~# smartctl -i /dev/sda
smartctl 7.1 2019-12-30 r5022 [armv7l-linux-5.4.72-v7l+] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Western Digital Red
Device Model:     WDC WD40EFRX-68N32N0
Serial Number:    WD-WCC7K4CD101H
LU WWN Device Id: 5 0014ee 20fa00e6e
Firmware Version: 82.00A82
User Capacity:    4,000,787,030,016 bytes [4.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    5400 rpm
Form Factor:      3.5 inches
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-3 T13/2161-D revision 5
SATA Version is:  SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Mon Nov 16 00:51:13 2020 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

 From smartd...

Nov 16 00:19:50 pi4modelb1.[redacted] smartd[5105]: Warning via to 
[redacted]: successful
Nov 16 00:19:52 pi4modelb1.[redacted] smartd[5105]: Device: /dev/sda 
[SAT], failed to read SMART Attribute Data
Nov 16 00:19:52 pi4modelb1.[redacted] smartd[5105]: Sending warning via 
to [redacted] ...
Nov 16 00:19:52 pi4modelb1.[redacted] smartd[5105]: Warning via to 
[redacted]: successful
Nov 16 00:20:00 pi4modelb1.[redacted] smartd[5105]: Device: /dev/sdb 
[SAT], not capable of SMART self-check
Nov 16 00:20:00 pi4modelb1.[redacted] smartd[5105]: Sending warning via 
to [redacted] ...
Nov 16 00:20:00 pi4modelb1.[redacted] smartd[5105]: Warning via to 
[redacted]: successful
Nov 16 00:20:02 pi4modelb1.[redacted] smartd[5105]: Device: /dev/sdb 
[SAT], failed to read SMART Attribute Data
Nov 16 00:20:02 pi4modelb1.[redacted] smartd[5105]: Sending warning via 
to [redacted] ...
Nov 16 00:20:02 pi4modelb1.[redacted] smartd[5105]: Warning via to 
[redacted]: successful

 From smartd.conf...  Is my understanding that per the documentation, 
ANY THING after the DEVICESAN line is IGNORED, this per the 
documentation in the default smartd.conf file.

/dev/sda -m [redacted] -M test
/dev/sdb -m [redacted] -M test

DEVICESCAN -d removable -n standby -m root -M exec 
/usr/share/smartmontools/smartd-runner

/dev/sda -l error \
          -l selftest \
          -t \      # Attributes not tracked:
          -I 194 \  # temperature
          -I 231 \  # also temperature
          -I 9      # power-on hours
          -m [redacted]

/dev/sda -l error \
          -l selftest \
          -t \      # Attributes not tracked:
          -I 194 \  # temperature
          -I 231 \  # also temperature
          -I 9      # power-on hours
          -m [redacted]