Hitachi hard disk drive specifications
217
Any Attribute Values accumulated and saved to volatile memory prior to receipt of the SMART Disable
Operations command will be preserved in the device‟s Attribute Data Sectors. If the device is re-enabled, these
Attribute Values will be updated, as needed, upon receipt of a SMART Read Attribute Values or SMART Save
Attribute Values command.
11.43.1.10
SMART Return Status (Subcommand Dah)
This command is used to communicate the reliability status of the device to the host‟s request. Upon receipt of
the SMART Return Status subcommand the device saves any updated Pre-failure type Attribute Values to the
reserved sector and compares the updated Attribute Values to the Attribute Thresholds.
If the device does not detect a Threshold Exceeded Condition, the device loads 4Fh into the Cylinder Low
register, C2h into the Cylinder High register.
If the device detects a Threshold Exceeded Condition, the device loads F4h into the Cylinder Low register, 2Ch
into the Cylinder High register.
11.43.1.11
SMART Enable/Disable Automatic Off-Line (Subcommand DBh)
This subcommand enables and disables the optional feature that causes the device to perform the set of off-line
data collection activities that automatically collect attribute data in an off-line mode and then save this data to the
device‟s non-volatile memory. This subcommand may either cause the device to automatically initiate or resume
performance of its off-line data collection activities or cause the automatic off-line data collection feature to be
disabled.
A value of zero written by the host into the device‟s Sector Count Register before issuing this subcommand shall
cause the feature to be disabled. Disabling this feature does not preclude the device from saving attribute values
to non-volatile memory during some other normal operation such as during a power-on or power-off sequence or
during an error recovery sequence.
A value of F8h written by the host into the device‟s Sector Count Register before issuing this subcommand shall
cause this feature to be enabled. Any other non-zero value written by the host into this register before issuing
this subcommand is vender specific and will not change the current Automatic Off-Line Data Collection, but the
device may respond with the error code specified in 0 on the page.230