User manual

Hitachi hard disk drive specifications
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9.10 Power-up in Standby feature set
Power-Up In Standby feature set allows devices to be powered-up into the Standby power management state to
minimize inrush current at power-up and to allow the host to sequence the spin-up of devices.
This feature set will be enabled/disabled via the SET FEATURES command. The enabling of this feature set
shall be persistent after power cycle.
A device needs a SET FEATURES subcommand to spin-up to active state when the device has powered-up into
Standby. The device remains in Standby until the SET FEATURES subcommand is received.
If power-up into Standby is enabled, when an IDENTIFY DEVICE is received while the device is in Standby as a
result of powering up into Standby, the device shall set word 0 bit 2 to one to indicate that the response is
incomplete, then only words 0 and 2 are correctly reported.
The IDENTIFY DEVICE information indicates the states as follows:
 identify device information is complete or incomplete
 this feature set is implemented
 this feature set is enabled or disabled
 the device needs the Set Features command to spin-up into active state
9.11 Advanced Power Management feature set (APM)
This feature allows the host to select an advanced power management level. The advanced power management
level is a scale from the lowest power consumption setting of 01h to the maximum performance level of FEh.
Device performance may increase with increasing advanced power management levels. Device power
consumption may increase with increasing advanced power management levels. The advanced power
management levels contain discrete bands, described in the section of Set Feature command in detail. This
feature set uses the following functions:
1. A SET FEATURES subcommand to enable Advanced Power Management
2. A SET FEATURES subcommand to disable Advanced Power Management
Advanced Power Management is independent of the Standby timer setting. If both Advanced Power
Management and the Standby timer are set, the device will go to the Standby state when the timer times out or
the device‟s Advanced Power Management algorithm indicates that the Standby state should be entered.
The IDENTIFY DEVICE response word 83, bit 3 indicates that Advanced Power Management feature is
supported if set. Word 86, bit 3 indicates that Advanced Power Management is enabled if set. Word 91, bits 7-0
contain the current Advanced Power Management level if Advanced Power Management is enabled.