HP 9000 Virtual Library System - Manual (Page 95)

NOTE: It is not necessary to power off a disk array enclosure when replacing a power module,
hard drive, RAID controller, or expansion controller.
To power off a VLS array:
1.
Power off the system. See “Powering Off the System” (page 94) .
2. Turn both power switches on the rear of each disk array enclosure off. Some power supply
models do not have a power switch; in this case, power down the enclosure by unplugging
the power cord from the enclosure.
Always power off the base enclosure first. Then power off the capacity enclosures, starting
with the capacity enclosure at the beginning of the SAS chain and working away from the
base enclosure.
Powering Off VLS Arrays 95