9. Turn off both power switches on the back of each storage expansion enclosure
in the configuration.
CAUTION:
The power switch on the power supply and fan unit does not turn off the
electrical current supplied to the device. The DS5020 storage subsystem
might also have more than one connection to ac power. Toremove all
electrical current from the device, ensure that all ac power cords are
disconnected from the power supply and fan unit ac input connectors.
10. Remove (unplug) all of the power cords from the DS5020 power supply
connectors.
11. After you perform the necessary maintenance procedures, turn on the power
using the procedure in “Turning on the storage subsystem” on page 95.
Performing an emergency shutdown
Attention: Emergency situations might include fire, flood, extreme weather
conditions, or other hazardous circumstances. If a power outage or emergency
situation occurs, always turn off all power switches on all computing equipment.
This helps to safeguard your equipment from potential damage due to electrical
surges when power is restored. If the storage subsystem loses power unexpectedly,
it might be due to a hardware failure in the power system or in the midplane.
Complete the following steps to shut down the system during an emergency:
1. If you have time, stop all I/O activity to the storage subsystem by shutting down
the host or disconnecting the storage subsystem logical drives through the host.
2. Check the LEDs. Make note of any Needs Attention LEDs that are on so you
can correct the problem when you turn on the power again.
3. Turn off all power supply switches, starting with the DS5020 storage subsystem
first, and followed by the storage expansion enclosures. Then, unplug the power
cables from the storage subsystem.
CAUTION:
This unit has more than one power source. To remove all power from the
unit, all MAINS must be disconnected.
CAUTION:
The power switch on the power supply and fan unit does not turn off the
electrical current supplied to the device. The DS5020 storage subsystem
might also have more than one connection to ac power. Toremove all
electrical current from the device, ensure that all power cords are
disconnected from the power supply and fan unit input connectors.
Restoring power after an unexpected shutdown
Use the following procedure to restore power to the storage subsystem in a
configuration after an unplanned shutdown.
112 IBM System Storage DS5020 Storage Subsystem: Installation, User ’s, and Maintenance Guide