hdparm useful commands

Some useful commands:
This check current IDE power mode status of the disk:
– unknown (drive does not support this command),
– active/idle (normal operation),
– standby (low power mode, drive has spun down),
– sleeping (lowest power mode, drive is completely shut down)
The operators: -S, -y, -Y, -Z can be used to manipulate the IDE power modes

hdparm -C /dev/sda

Force an IDE drive to immediately enter the low power consumption STANDBY mode, usually causing it to spin down:

hdparm -y /dev/sda

Force  an  IDE  drive to immediately enter the lowest power consumption sleep mode, causing it to shut down completely. A hard or soft reset is required before the drive can be accessed again:

hdparm -Y /dev/sda

Put the drive into idle  (low-power)  mode,  and  also  set  the standby (spindown) timeout for the drive.  This timeout value is used by the drive to determine how long to wait  (with  no  disk activity)  before  turning  off the spindle motor to save power:

hdparm -S /dev/sda

Disable  the  automatic power-saving function of certain Seagate drives (ST3xxx models?), to prevent them  from  idling/spinning down at inconvenient times.
An example:

hdparm -y /dev/sdd
/dev/sdd
      issuing standby command
hdparm -C /dev/sdd
/dev/sdd
      drive state is: standby