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set power mode

The set power mode control function changes the drive power mode to one of four modes: active, standby, idle, and sleep. It can be used to reduce drive power consumption.

In the idle mode, the nonessential electronics on the ATA hard drive are disabled. For example, the read and write channels are disabled during the idle state. The spindle motor remains enabled during the idle state, so the drive still responds immediately to any commands requesting media access.

In the standby mode, the head is parked and the spindle motor is disabled. The drive interface remains active and is still capable of responding to commands. However, it can take several seconds to respond to media access commands, because the drive's spindle motor must return to full speed before media access can take place.

In the sleep mode, both the drive interface and the spindle motor are disabled. The driver must reset and reconfigure the drive before another access to the drive can be made. Since many drives do not support the sleep mode, and because there is little power savings difference between standby and sleep modes, the ATA disk driver may put the drive in standby mode instead.


Parameter block

-->

csCode

A value of 70.
-->

ioVRefNum

 The logical drive number.
-->

csParam[0]

 The most significant byte contains one of the following codes:
0 = enable the active mode
1 = enable the standby mode
2 = enable the idle mode
3 = enable the sleep mode
<--

ioResult

 See result codes.
RESULT CODES

noErr

 0 Successful completion, no error occurred.

controlErr

 -17 The power management information couldn't be returned due to a manager error.

nsDrvErr

 -56 The specified logical drive number does not exist.
© 1999 Apple Computer, Inc. — (Last Updated 30 Oct 97)

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