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Chapter 2. Introducing SSA Loops
This chapter describes the principles of SSA loops, how SSA devices are known to the
system programs, and the rules that you must observe when you configure your SSA
loops.
Loops, Links, and Data Paths
In the simplest SSA configuration, SSA devices are connected through two or more
SSA links to an SSA adapter that is located in a using system. The devices, SSA links,
and SSA adapter are configured in loops. Each loop provides a data path that starts at
one connector of the SSA adapter and passes through a link (SSA cable) to the
devices. The loop continues through the devices, then returns through another link to a
second connector on the SSA adapter.
The maximum permitted length for an external copper cable that connects two SSA
nodes (for example, disk drives) is 25 meters (82 feet).
The maximum permitted length for an external fiber optic cable that connects two SSA
nodes (for example, disk drives) is 10 kilometers (32800 feet). Some devices, however,
can operate only at shorter distances. See your subsystem documentation for details.
Details of the rules for configuring SSA loops are given for each SSA adapter in "Rules
for SSA Loops" on page 22.
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