HP Array Controller HSG V8.7 Software - Manual (Page 154)

Storage Devices
7–8 UltraSCSI RAID Enclosure
Hot Swap
When performing a hot swap, power and data are present on the disk
drive SBB backplane connector.
Caution
Although the HSZ70 series array controllers support hot
swap, other controllers do not. Refer to the array controller
documentation to determine which array
controller-supported swap method to use.
If you are not positive that your SCSI controller supports
hot swap, Compaq recommends using warm swap to protect
data integrity.
Use hot swap to remove and replace disk drive SBBs from a system
that is online and active.
Warm Swap
When performing a warm swap, power is present on the disk drive
SBB plug connector and there is no data on the bus. Before
performing a warm swap, quiesce the bus at the array controller and
observe the green activity status LED on the disk drive SBB to ensure
that it is not F
LASHING .
Caution
Perform a warm swap only when the green device activity
LED is O
FF .
Cold Swap
When performing a cold swap, neither power nor data is present on
the disk drive SBB plug connector. This requires turning O
FF the
enclosure power in all the UltraSCSI RAID subsystem enclosures.