3.8.4Power-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 modes | Heads | Spindle | Buffer |
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Active | Tracking | Rotating | Enabled |
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Idle_a | ID Biased | Rotating | Enabled |
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Idle_b | Parked | Rotating | Enabled |
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Idle_c | Parked | Rotating at lower RPM | Enabled |
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Standby | Parked | Stopped | Enabled |
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Sleep | Parked | Stopped | Disabled |
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•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 enabled, 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 buf- fer is disabled, 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.
3.8.4.1Extended Power Conditions - PowerChoiceTM
Utilizing the load/unload architecture a programmable power management interface is provided to tailor sys- tems for reduced power consumption and performance requirements.
The table below lists the supported power conditions available in PowerChoice. Power conditions are ordered from highest power consumption (and shortest recovery time) to lowest power consumption (and longest recovery time) as follows: Idle_a power >= Idle_b power >= Idle_c power >= Standby_z power. The further you go down in the table, the more power savings is actualized. For example, Idle_b results in greater power sav- ings than the Idle_a power condition. Standby results in the greatest power savings.
Constellation.2 Serial ATA Product Manual, Rev. B | 15 |
