IBM Advanced SerialRAID Adapters SA33-3285-02, User Manual

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Simple Loop
Figure 2 shows a simple SSA loop. The devices that are attached to the SSA adapter
card
1
are connected through SSA links
2
. These SSA links are configured as a
loop. Data and commands to a particular device pass through all other devices on the
link between the adapter and the target device.
Data can travel in either direction round the loop. The adapter can, therefore, get
access to the devices
3
(disk drives in this example) through two data paths. The
adapter always, however, uses the path that has the fewest interconnecting devices
between the adapter and the destination device. The using system cannot detect which
data path is being used.
Using system
Disk
1
Disk
2
Disk
3
Disk
4
Disk
5
Disk
6
Disk
7
Disk
8
A1 A2 B1 B2
Figure 2. Simple Loop
8
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