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Figure 13-6 shows two PSUs present in the control and expansion enclosure. The controller 
PSU has two green and one amber indication LEDs that report the status of the PSU. 
Figure 13-6   Controller and expansion enclosure LED status indicator
Figure 13-7 presents the rear overview of the enclosure canister with a PSU. In contrast to 
the control enclosure, these PSUs do not have a power switch. The enclosure is powered on 
by the direct attachment of a power cable.
Figure 13-7   Expansion enclosure power supply unit
Power supplies in both control and expansion enclosures are hot-swappable and replaceable 
without a need to shut down a node or cluster. If the power is interrupted in one node for less 
than 5 seconds, the canister does not perform a fire hose dump, and continues operation 
from the battery. This feature is useful for a case of, for example, maintenance of UPS 
systems in the data center or replugging the power to a different power source or PDU unit. A 
fully charged battery can perform two fire hose dumps.
13.2  Shutting down IBM Storwize V7000
You can safely shut down an IBM Storwize V7000 system by using the GUI or CLI.
Before shutting down IBM Storwize V7000, stop all hosts that have allocated volumes from 
the device. This step can be skipped for hosts that have volumes that are also provisioned 
with mirroring (host-based mirror) from different storage devices. However, doing so incurs 
errors that are related to lost storage paths/disks on the host error log.
PSU1 PSU2
PSU
Important: Never shut down your IBM Storwize V7000 system by powering off the PSUs, 
removing both PSUs, or removing both power cables from a running system. It can lead to 
inconsistency or loss of the data that is staged in the cache.