IBM Advanced SerialRAID Adapters SA33-3285-02 User Manual page 472

Example 1
If the SRN is 24002, the device is connected to adapter port 0 (shown as A1 on
the screen), and has an SSA address of 02 (shown as 2 on the screen). In the
example screen, that device is pdisk3, which is the first device of the two. The
second device is pdisk2 (PAA−1).
If the SRN is 33002, the first device of the two is again pdisk3. The second
device is pdisk4 (PAA+1).
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