Seagate Enterprise Performance - 3.5 HDD SAS Product Manual, Rev. B
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6.0
Physical/electrical specifications
This section provides information relating to the physical and electrical characteristics of the drive.
6.1
PowerChoice
TM
power management
Drives using the load/unload architecture provide programmable power management to tailor systems for performance and greater energy
efficiency.
The table below lists the supported PowerChoice modes. The further down in the table, the more power savings can be realized. For example,
Idle_B mode results in greater power savings than Idle_A mode. Standby_Z mode results in the greatest power savings.
PowerChoice modes
PowerChoice
TM
can be invoked using one of these two methods:
• Power Condition mode page method—Enable and initialize the idle condition timers and/or the standby condition timers. The timer values are
based on the values set in the Power Condition mode page.
• START STOP UNIT command method—Use the START STOP UNIT command (OPERATION CODE 1Bh). This allows the host to directly transition the
drive to any supported PowerChoice mode.
If both the Power Condition mode page and START STOP UNIT command methods are used, the START STOP UNIT command request takes
precedence over the Power Condition mode page power control and may disable the idle condition and standby condition timers. The REQUEST
SENSE command reports the current PowerChoice state if active and also the method by which the drive entered the PowerChoice state.
When the drive receives a command, all power condition timers are suspended if they were enabled via the Power Condition mode page. Once all
outstanding commands are processed, the power condition timers are reinitialized to the values defined in the Power Condition mode page
6.1.1
PowerChoice reporting methods
PowerChoice
TM
provides these reporting methods for tracking purposes:
Request Sense command reports
• Current power condition
• Method of entry
.
Mode Sense command reports (mode page 0x1A)
• Idle conditions enabled / disabled
• Idle condition timer values (100ms increments) (default, saved, current, changeable)
Power Condition Vital Product Data (VPD) Page (VPD page 0x8A)
• Supported power conditions
• Typical recovery time from power conditions (1ms increments)
Start/Stop Cycle Counter Log Page reports (log page 0x0E)
• Specified and accumulated Start/Stops and Load/Unload cycles
Power Condition Transitions Log Page reports (log page 0x1A, subpage 0x00)
• Accumulated transitions to Active, Idle_A, Idle_B, Idle_C, Standby_Y, Standby_Z
Mode
Description
Idle_A
Reduced electronics
Idle_B
Heads unloaded. Disks spinning at full RPM
Idle_C
Heads unloaded. Disks spinning at reduced RPM
Standby_Y
Heads unloaded. Disks spinning at reduced RPM.
Recovery requires the NOTIFY (Enable Spinup) command.
Standby_Z
Heads unloaded. Motor stopped (disks not spinning)
Recovery requires the NOTIFY (Enable Spinup) command.
Note
Processing the Request Sense command does not impact the drive’s power save state.
