After having installed smartmontools, I had this message in the /var/log/syslog file :
smartd: Problem creating device name scan list
By default, the smartd daemon will look for all hard drives in your server.
If you only have one, you can replace DEVICESCAN by the pathname of your disk in the smartd config file /etc/smartd.conf. For instance, /dev/sda can if it is a SATA hard drive.
Instead of this line :
DEVICESCAN -a -d sat -m root -M exec /usr/share/smartmontools/smartd-runner
write this one :
/dev/sda -a -d sat -m root -M exec /usr/share/smartmontools/smartd-runner
And then restart the smartd daemon :
root@localhost:~# /etc/init.d/smartmontools restart