Examples: Switchable independent disk pools

In a multisystem environment, an independent disk pool can be switched between servers in a cluster. A switchable independent disk pool is a set of disk units that you can switch between servers so that each server can access the data. Only one system can access the data at a time.

Switchable independent disk pools can reside on one of two types of switchable hardware devices:

External expansion unit

The switchable device can be an external expansion unit connected to the clustered servers on the same high-speed link (HSL) loop.

Input/output processor (IOP) in a logical partition

In an LPAR environment, the switchable device can be an IOP on the bus shared by the partitions or in an I/O pool.

The entity that switches is actually the expansion unit or the IOP containing the independent disk pool. When an expansion unit or IOP is switched, all of the hardware attached to the switchable entity is moved to the backup system.

The following example configurations and scenario illustrate some typical switchable independent disk pools implementations:

• Example: Switchable expansion unit
  
• Example: Switchable IOP with logical partitions
  
• Example: Switchable expansion unit with logical partitions
  
• Scenario: Consolidate servers using switchable independent disk pools
  
• Example: Independent disk pools with geographic mirroring