IBM H SERIES RS/6000 - Manual (Page 39)

Disk Drive Status LED States
SCSI Disk Drives: The following table explains the meaning of the green and
amber status LEDs and spin down button.
Amber
Green
Spin Down Button
Status LEDs
LED or Button Status Definition
Amber On Drive spinning
Off Drive not spinning
Green On Power On
Off Power Off
Blinking Power Off/Drive identify
Spin down Depressed Spin down drive and remove power
Chapter 2. Using the System Unit 2-19