Eu experimentei o mesmo problema, então fiz algumas pesquisas. Eu encontrei isto:
/etc/smartd.conf
# smartd will re-read the configuration file if it receives a HUP
# signal
# The file gives a list of devices to monitor using smartd, with one
# device per line. Text after a hash (#) is ignored, and you may use
# spaces and tabs for white space. You may use '\' to continue lines.
# You can usually identify which hard disks are on your system by
# looking in /proc/ide and in /proc/scsi.
# The word DEVICESCAN will cause any remaining lines in this
# configuration file to be ignored: it tells smartd to scan for all
# ATA and SCSI devices. DEVICESCAN may be followed by any of the
# Directives listed below, which will be applied to all devices that
# are found. Most users should comment out DEVICESCAN and explicitly
# list the devices that they wish to monitor.
Eu suponho que cancelar o registro da unidade do kernel via
root@localhost# echo 1 > /sys/block/sdX/device/delete
em seguida, remover a entrada do dispositivo do /etc/smartd.conf,
em seguida, o "serviço sudo smartmontools restart" corrigirá seu problema e o smartd interromperá o relatório da unidade ausente.