Simple Loop - One Disk Drive Missing - IBM Advanced SerialRAID Adapters SA33-3285-02 User Manual

Simple Loop — One Disk Drive Missing
If a disk drive fails, or is switched off, the loop is broken, and one of the data paths to a
particular disk drive is no longer available. The disk drives on the remainder of the loop
continue to work, but an error is reported to the system. The adapter now uses the
alternative path to some of the devices.
In Figure 3, disk drive number 3 has failed. Disk drives 1 and 2 can communicate with
the using system only through connector A1 of the SSA adapter. Disk drives 4 through
8 can communicate only through connector A2 of the SSA adapter.
Using system
A1 A2 B1 B2
Disk Disk Disk Disk Disk Disk Disk Disk
1 2 3 4 5 6 7 8
Figure 3. Simple Loop with One Disk Drive Missing
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Chapter 2. Introducing SSA Loops