Advanced Power Management - Fujitsu MHU2100AT Product Manual

Device Overview
Emergency Unload other than Normal Unload is performed when the power is
shut down while the heads are still loaded on the disk.
The product supports the Emergency Unload a minimum of 20,000 times.
When the power is shut down, the controlled Normal Unload cannot be executed.
Therefore, the number of Emergency other than Normal Unload is specified.
Remark:
We recommend cutting the power supply of the HDD for this device after the
Head Unload operation completes. The recommended power supply cutting
sequence for this device is as follows:
1) Disk Flush
Flush Cache command execution.
2) Head Unload
Standby Immediate command execution.
3) Wait Status
Checking whether bit 7 of the status register was set to '0'.
(wait to complete STANDBY IMMEDIATE command)
4) HDD power supply cutting

1.11 Advanced Power Management

The disk drive automatically shifts to the power saving mode according to the
setting of the APM mode under the idle condition.
The APM mode can be chosen with a Sector Count register of the SET
FEATURES(EF) command.
The disk drive complies with the three kinds of APM modes that a command
from the host is required.
FR = 05h : Enable APM
SC = C0h - FEh :
SC = 80h - BFh :
SC = 01h - 7Fh :
FR = 85h : Disable APM (Set Mode-0)
Active Idle:
Low Power Idle:
1-12
Mode-0 Active Idle → Low Power Idle
Mode-1 Active Idle → Low Power Idle (Default)
Mode-2 Active Idle → Low Power Idle → Standby
The head is in a position of extreme inner in disk
medium. (VCM Lock)
The head is unloaded from disk.
The spindle motor rotates.
C141-E202-01EN