Fujitsu MHR2010AT Product Manual page 141

(29) SMART (X'B0)
This command predicts the occurrence of device failures depending on the
subcommand specified in the FR register. If the FR register contains values that
are not supported with the command, the Aborted Command error is issued.
Before issuing the command, the host must set the key values in the CL and CH
registers (4Fh in the CL register and C2h in the CH register). If the key values
are incorrect, the Aborted Command error is issued.
If the failure prediction function is disabled, the device returns the Aborted
Command error to subcommands other than those of the SMART Enable
Operations (with the FR register set to D8h).
If the failure prediction function is enabled, the device collects and updates data
on specific items. The values of items whose data is collected and updated by the
device in order to predict device failures are hereinafter referred to as attribute
values.
C141-E145-02EN
5.3 Host Commands
5-67