S.M.A.R.T. not supported in AHCI mode

[James]

The S.M.A.R.T. settings are not available through the gnome-disks GUI on a Dell Inspiron 15 3000 Series laptop.

The hard drive and BIOS support S.M.A.R.T., however.

A workaround is to go into the BIOS and change the SATA mode from AHCI to legacy ATA.

HOWEVER, this workaround should not be necessary because, although the command-line tool smartctl SEEMS not to work in AHCI mode, passing it the -d ata flag (overriding its default IDE mode which required the hard drive controller's legacy ATA mode) allows it to read S.M.A.R.T. data from the hard drive while in AHCI mode.

tl;dr: gnome-disks does not support S.M.A.R.T. over ACHI, even though there are no technical obstacles (such as ioctls, drivers, etc) to supporting it.