IBM SAN Volume Controller 2145-CG8, Hardware Installation Manual

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If a redundant ac-power switch is not used, the two uninterruptible power
supplies that power an I/O group can be connected to different, independent
electrical power sources. In this case, if a single power source fails, only one node
in the I/O group stops and the SAN Volume Controller system can continue to
operate, although with reduced performance.
Each uninterruptible power supply must be in the same rack as the node that it
powers.
Each 2145 UPS-1U includes one power cord that connects the uninterruptible
power supply to a redundant ac-power switch, if one exists, or to a rack power
distribution unit (PDU), if one exists. The 2145 UPS-1U also includes an alternative
power cable to connect to an external power source that is specific to your
geography.
Each 2145 UPS-1U is connected to a SAN Volume Controller node with a power
cable and a signal cable. To avoid the possibility of power and signal cables being
connected to different uninterruptible power supplies, these cables are wrapped
together and supplied as a single field-replaceable unit (FRU). The SAN Volume
Controller node reads status and identification information from the
uninterruptible power supply using the signal cable.
Chapter 1. SAN Volume Controller overview
5