Fujitsu MHV2080AS manual Features register values subcommands and functions 3, Smart Return Status

Interface

Table 5.7 Features register values (subcommands) and functions (3 of 3)

Features Resister	Function
X’DA’	SMART RETURN STATUS:
	When the device receives this subcommand, it asserts the BSY bit and saves the
	current device attribute values. Then the device compares the device attribute
	values with insurance failure threshold values. If there is an attribute value
	exceeding the threshold, F4h and 2Ch are loaded into the CL and CH registers.
	If there are no attribute values exceeding the thresholds, 4Fh and C2h are loaded
	into the CL and CH registers. After the settings for the CL and CH registers
	have been determined, the device clears the BSY bit
X’DB’	SMART ENABLE/DISABLE AUTO OFF-LINE:
	This sets automatic off-line data collection in the enabled (when the SC
	register specification ≠ 00h) or disabled (when the SC register specification
	= 00) state. This setting is preserved whether the drive’s power is switched
	on or off.
	If 24 hours have passed since the power was switched on, or since the last
	time that off-line data were collected, off-line data collection is performed
	without relation to any command from the host computer.

The host must regularly issue the SMART READ DATA subcommand (FR register = D0h), SMART SAVE ATTRIBUTE VALUES subcommand (FR register = D3h), or SMART RETURN STATUS subcommand (FR register = DAh) to save the device attribute value data on a medium.

Alternatively, the device must issue the SMART ENABLE-DISABLE ATTRIBUTE AUTOSAVE subcommand (FR register = D2h) to use a feature which regularly saves the device attribute value data to a medium.

The host can predict failures in the device by periodically issuing the SMART RETURN STATUS subcommand (FR register = DAh) to reference the CL and CH registers.

If an attribute value is below the insurance failure threshold value, the device is about to fail or the device is nearing the end of its life . In this case, the host recommends that the user quickly back up the data.

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