Seagate ST9120817AS - Momentus 5400.4 120 GB Hard Drive, Product Manual

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10 Momentus 5400.4 SATA Product Manual, Rev. A
2.9.5 Power-management modes
The drive provides programmable power management to provide greater energy efficiency. In most systems,
you can control power management through the system setup program. The drive features the following
power-management modes:
• Active mode
The drive is in Active mode during the read/write and seek operations.
• Idle mode
The buffer remains enabled, and the drive accepts all commands and returns to Active mode any time disc
access is necessary.
• Standby mode
The drive enters Standby mode when the host sends a Standby Immediate command. If the host has set the
standby timer, the drive can also enter Standby mode automatically after the drive has been inactive for a
specifiable length of time. The standby timer delay is established using a Standby or Idle command. In Standby
mode, the
drive buffer is in Self Refresh Low Power mode, the heads are parked and the spindle is at rest.
The drive accepts all commands and returns to Active mode any time disc access is necessary.
• Sleep mode
The drive enters Sleep mode after receiving a Sleep command from the host. In Sleep mode, the drive buffer
is in Self Refresh Low Power mode, the heads are parked and the spindle is at rest. The drive leaves Sleep
mode after it receives a Hard Reset or Soft Reset from the host. After receiving a reset, the drive exits Sleep
mode and enters Standby mode with all current translation parameters intact.
• Idle and Standby timers
Each time the drive performs an Active function (read, write or seek), the standby timer is reinitialized and
begins counting down from its specified delay times to zero. If the standby timer reaches zero before any
drive activity is required, the drive makes a transition to Standby mode. In both Idle and Standby mode, the
drive accepts all commands and returns to Active mode when disc access is necessary.
Table 4: Power management modes
Power modes Heads Spindle Buffer
Active (operating) Tracking Rotating Full power
Idle, performance Tracking Rotating Low power
Idle, active Bias against crash stops Rotating Self refresh—low power
Idle, low power Parked Rotating Self refresh—low power
Standby Parked Stopped Self refresh—low power
Sleep Parked Stopped Self refresh—low power