Hitachi hard disk drive specifications
103
9.19.2 Power condition timers
The device shall have manufacturer specified power-on default settings for the power condition timers. Power
condition timers are changeable with the SET FEATURES Extended Power Conditions subcommand. Extended
Power Conditions doesn't become Enable as long as Timer is not adjusted to an effective value by using the
subcommand of EPC. When all Timer is zero, EPC becomes Disable.Configured settings for the timers shall be
readable in the Power Conditions log.
A power condition timer set to zero indicates that the associated power condition is disabled. Power becomes
Enable at the value whose timer is larger than ZERO.
The IDENTIFY DEVICE command indicates if this feature set is supported Word 119 bit7, and if there are power
condition timers enabled Word120 bit 7.
If the EPC is enabled, then the value of each timer specifies the time after command completion that
the device shall wait before transitioning to the power condition . All enabled power condition timers run
concurrently .
As a result of processing any command, the device may change to a different power condition.
When an enabled timer expires, the device shall transition to the power condition associated with that timer.
Timer expirations shall only cause the device to transition from higher power conditions to lower power
conditions (e.g., if the Standby_z timer is set to a smaller interval than the Idle_b timer, and the device is
currently in the Standby_z power condition, then the device shall remain in the Standby_z power condition when
the Idle_b timer expires). If the timer expiration qualifies the device to transition to more than one enabled power
condition, then the device shall transition to the power condition with the least power consumption.
9.19.3 Interaction with resets, commands and other features
On successful processing of a power cycle, the device shall:
When EPC is Enable, the following content is executed.
1) copy the Saved Timer Settings to the Current Timer Settings, for all supported power Conditions.
2) reinitialize and restart all enabled EPC timers with Current values.
On successful processing of a hardware reset, a software reset, or a DEVICE RESET command, the device
shall:
When EPC is Enable, the following content is executed.
1) remain in the current power condition.
2) reinitialize and restart all enabled EPC timers with Current values.
The Extended Power Conditions and the Advanced Power Management features are mutually exclusive of each
other. All EPC subcommands shall return command aborted if APM is enabled. The SET FEATURES
Enable/Disable APM subcommands shall abort if IDENTIFY DEVICE data word 120 bit 7 is set to one.
CheckPowerMode returns the same result as EPC NotSupport.
During background activities, all EPC timers may be paused. On completion of the activity, any paused EPC
timers shall be continued from where they were paused.
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