Digital Equipment EK-SFXXS-SG-003, Руководство по обслуживанию

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2–6 Theory of Operation
2.2.2 SF3x Operating Modes
SF3x series storage enclosures can operate in either through-bus or
split-bus mode. These modes are described in the following sections.
2.2.2.1 Through-Bus Mode
In through-bus mode, all six disk ISEs in each half of the storage
enclosure are connected to the same DSSI bus. The DSSI bus enters
through the left DSSI connector on the top of the backplane, connects
to the ISEs in slots A, C, and E on the left side of the enclosure, then
goes through the ISEs in slots F, D, and B, and finally out the right DSSI
connector.
At this point, the DSSI bus is either terminated, with a DSSI terminator,
(PN 12–31281–01), connected to a magazine tape ISE, or connected to the
DECarray I/O panel.
2.2.2.2 Split-Bus Mode
Each set of ISEs (front and rear) can be further separated by putting the
ISEs on the left (slots A, C, and E) and the ISEs on the right (slots B, D,
and F) on separate DSSI buses. This configuration leaves each enclosure
with four distinct DSSI buses, each with three ISEs.
To configure an SF3x enclosure in split-bus mode it is necessary to remove
the jumper cable from the DSSI backplane and put DSSI terminators (PN
12-28976-01) on the connectors where the jumper cable was attached.
2.2.3 Front Panel Controls, Labels, and Indicators
Figure 2–2 shows a front view of the storage enclosure. The OCP is on
the top front of the enclosure. It can be accessed without opening the
cabinet front door.
The dc power switches for each ISE are on the bottom front of the
enclosure. These switches are not accessible when the front door of
the cabinet is closed.