Planning switched logical units (LUNs)
A single copy of the data is maintained on the logical units within the IBM® System Storage™ storage unit.
When an outage occurs on the primary node, access to the data on the switchable logical units switches to a designated backup node. Additionally, independent disk pools can be used in a cross-site mirroring (XSM) environment. This allows a mirror copy of the independent disk pool to be maintained on a system that is (optionally) geographically distant from the originating site for availability or protection purposes.
Careful planning is required if you plan to take advantage of switchable logical units residing on independent disk pools or cross-site mirroring (XSM).
You should also evaluate your current system disk configuration to determine if additional disk units may be necessary. Similar to any system disk configuration, the number of disk units available to the application can have a significant affect on its performance. Putting additional workload on a limited number of disk units might result in longer disk waits and ultimately longer response times to the application. This is particularly important when it comes to temporary storage in a system configured with independent disk pools. All temporary storage is written to the SYSBAS disk pool. If your application does not use much temporary storage, then you can get by with fewer disk arms in the SYSBAS disk pool. You must also remember that the operating system and basic functions occur in the SYSBAS disk pool.
Before you can use IBM® Navigator for i to perform any disk management tasks, such as creating an independent disk pool, you need to set up the proper authorizations for dedicated service tools (DST).