IBM DS8800, Introduction And Planning Manual, Page: 25 / 256

v For each PPS in each model, a booster module is added. When the BBUs supply
power to the primary power bus, battery power is fed into the booster module,
which in turn keeps disk enclosure power present.
v
Batteries will be added to expansion models that do not already have them. The
base model and the first expansion model will already have BBUs but
subsequent expansion models will not include BBUs until the EPLD feature is
installed.
With the addition of this hardware, the DS8000 will be able to run for
approximately 60 seconds on battery power before the processor enclosures
begin to copy NVS data to internal disk and then shut down. This allows for up
to a 60-second interruption to line power with no outage to the DS8000.
Figure 2 provides a high-level view of the components of an expansion model
(Model 94E).
The following notes provide additional information about the labeled components
in Figure 2:
1. The rack power and cooling area of each expansion model provide the power
and cooling components needed to run the frame.
2. All expansion models can have up to 16 disk enclosures , which contain the disk
drives. In a maximum configuration, each expansion model can hold 256 disk
drives.
3. Expansion models can contain I/O enclosures and adapters if they are the first
expansion models that are attached to a Model 941 (4-way). If the expansion
model contains I/O enclosures, the enclosures provide connectivity between the
adapters and the processors. The adapters contained in the I/O enclosures can
be either device or host adapters.
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Figure 2. A 94E expansion model (with the back cover off) and its main components
Chapter 1. Introduction to IBM System Storage DS8000 series
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