IBM H SERIES RS/6000 - Manual (Page 40)

SSA Disk Drives: The following table explains the meaning of the Power, Ready
and Check status LEDs.
Locked Position
Power
Ready
Check
Status LEDs
LED Status Definition
Power On Power On
Off Power Off
Ready On Both SSA connections good and
drive is ready
Blinking Only one SSA connection good
Flickering Drive is executing a command
Check On Disk drive failure
Self-test running
Drive in service mode
Blinking Disk drive selected
2-20 RS/6000 Enterprise Server Model H Series User's Guide