DEVICESCAN doesn't know how to distinguish SATA drives. It leads into it trying to use them as SCSI discs, which naturally fails. You have to do -d ATA for both smartd and smartctl. But if you do that categorically in the smartd.conf, then the things might break for some users (actual SCSI, behind 3ware etc).

Couldn't smartmontools attempt to actually figure out what might work for all the devices? It would make the life of people trying get smart monitoring working out of the box for many people a lot nicer.

The only actually working way at this moment that I see is to add into /etc/init.d/smartmontools a function that scans all the hardware and at every reboot generates a new smartd.conf with forced correct device type setting for all the existent drives. Which sucks.