Comment 6 for bug 1540110

Maybe it is due to the fact (https://www.smartmontools.org/wiki/Supported_USB-Devices) that USB connected disks usually need a '-d' option to enable S.M.A.R.T. support.

In fact, for the same disk, trying first:

  $ sudo smartctl -d scsi -H -i -A -l error -l selftest '/dev/sdb'

gives "SMART support is: Unavailable - device lacks SMART capability.", whereas:

  $ sudo smartctl -d scsi -d sat -H -i -A -l error -l selftest '/dev/sdb'

gives "SMART support is: Available - device has SMART capability.//SMART support is: Enabled", and the full output expected.

And also in GSmartControl I have to add the "-d sat" option to Preferences/Drives to enable S.M.A.R.T. support and view attributes.

The difficulty to include this in gnome-disk-utility is that each disk needs a different "-d" option...