If using the hot spare function with a local class or shared class, the number of disks including the spare disks within the class is to be set to four or more. If the number of disks within the class is three, the spare disk will not be effective.
For the configuration in example 1, with only the SCSI Bus#0 malfunctioning, the class gets closed down and the transactions stop.
Figure 3.1 Example 1 of an unsuitable configuration
For the configuration in Example 2, after one of the disks has malfunctioned and the spare disk has been connected to the mirror group, the class gets closed down and transactions stop when one more disk malfunctions.
Figure 3.2 Example 2 of an unsuitable configuration
By increasing the number of disks within the class, it is possible to avoid the transaction stop caused by a single hardware malfunction.
Figure 3.3 Example 1 of a suitable configuration
If using the root class, insofar as there is a normal disk, the class will not close down, so setting the number of disks within the root class including the spare disk to three is not a problem.
Figure 3.4 Example 2 of a suitable configuration
Note
The hot spare function cannot be used in the root class in this version.
