IBM DS8800, Introduction And Planning Manual, Page: 31 / 256

Each expansion model contains two primary power supplies (PPSs)
4
. They
provide a redundant 208 V dc power distribution to the rack to convert the ac
input into dc power.
The power area contains a maximum of two BBUs
3
. The expansion model also
provides power distribution units
5
.
Note: The power area can contain zero or two BBUs, depending on your
configuration. The first expansion model requires two BBUs (with or
without EPLD). The second expansion model requires two BBUs (with
EPLD) and no BBUs without EPLD.
In a DS8800 4-way system, the first expansion model has four I/O enclosures
2
(with adapters). A second expansion model has no I/O enclosures. (You cannot
add an expansion model to a DS8800 2-way system.)
Figure 6 on page 10 shows an expansion model configured only with drives:
v
Storage enclosures (front) and power supplies to the storage enclosures and
FCIC cards (back)
1
v
Battery backup units (BBUs)
2
v Primary power supplies (PPSs)
3
v
Power distribution units
4
f2c01618
4
3
2
1
5
Figure 5. Expansion model (front and back views) of a Model 95E
Chapter 1. Introduction to IBM System Storage DS8000 series
9