IBM 7133 D40, Service Manual

Page: 72 / 306

Higher-Availability Configurations
For higher availability, you can connect more than one SSA attachment in an SSA loop,
if the attachments allow such a configuration.
In loops that have multiple SSA attachments, you can often get best performance if you
connect the attachments as equally as possible between the disk drive modules.
Figure 32 shows one 7133 connected in one loop with two SSA attachments.
The cables are described in “SSA Cables for 7133 Models D40 and T40” on page 56.
The internal connections of the 7133 are shown in “Internal Connections (Model D40)”
on page 28 and “Internal Connections (Model T40)” on page 30.
For information about the rules for SSA loops, see the “Rules for SSA Loops” on
page 47.
Figure 33 on page 55 shows three 7133s connected in one loop with six SSA
attachments. The broken line represents optional cables that provide additional
availability if a fault occurs.
1 1
2 2 2 2 2
7133 unit
4
8
1
12
4 3 2 1 5 6 7 8
9 10 11 12 13 14 15 16
13
5
9
16
Using system
A1 A2 B1 B2
Using system
A1 A2 B1 B2
Figure 32. Higher-Availability Configuration (One 7133)
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7133 Models D40 and T40 Service Guide