Mirrored protection is configured by disk pool because it is the user's level of control over single-level storage. Mirrored protection can be used to protect one, some, or all disk pools on a system. However, multiple disk pools are not required to use mirrored protection. Mirrored protection works well if all disk units on a system are configured into a single disk pool (the default on the iSeries™ server). In fact, mirroring reduces the need to partition auxiliary storage into disk pools for data protection and recovery. However, disk pools might still be desirable for performance and other reasons.
To provide the best protection and availability for the entire system, all disk pools in the system should have mirrored protection:
The disk units that are used in disk pools should be selected carefully. For best protection and performance, a disk pool should contain disk units that are attached to several different I/O processors. The number of disk units in the disk pool that are attached to each I/O processor should be the same (that is, balanced).