Seagate ST91000641SS ユーザーズマニュアル

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Constellation.2 SAS Product Manual, Rev. H

This section provides information relating to the physical and electrical characteristics of the drive.

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Drives using the load/unload architecture provide programmable power management to tailor systems for per-
formance and greater energy efficiency.

The table below lists the supported PowerChoice modes. The further you go down in the table, the more power 
savings you get. For example, Idle2 mode results in greater power savings than Idle1 mode. Standby mode 
results in the greatest power savings. 

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.

PowerChoice

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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 con-

dition 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.