Table 25-5 shows the application criteria for the system switchover facilities.

Table 25-5 System switchover facility application criteria

Importance	Standby system switchover facility	Standby-less system switchover (1:1) facility	Standby-less system switchover (effects distributed) facility
Transaction performance	Best	Poor	Good
	Maintains performance even when an error occurs. Guarantees the same throughput as during normal operations.	Load from alternate processing when an error occurs may impact processing performance. Load concentration on certain units reduces system throughput.	Load from alternate processing when an error occurs may impact processing performance. Load distribution is used to minimize system throughput degradation.
Resource requirement	Poor	Best	Best
	Needs standby server machines or system resources for standby units.	Does not need standby server machines or system resources for standby units.	Does not need standby server machines or system resources for standby units.
Handling of a series of errors	Best	Poor	Best
	Can handle based on linkage with cluster software (only when IP addresses are inherited, and not when the rapid system switchover facility is used).	Cannot handle because there is only one fixed alternate server.	Can handle based on linkage with cluster software.

Table 25-6 shows when each system switchover facility can be applied to a unit when a different system switchover facility is already being applied to another unit within the same system.

Table 25-6 Usability of each system switchover facility when another system switchover facility is already being used for another unit within the same system

Facility already being used	Usability of the standby system switchover facility	Usability of the standby-less system switchover (1:1) facility	Usability of the standby-less system switchover (effects distributed) facility
Standby system switchover facility	Y	Y	Y
Standby-less system switchover (1:1) facility	Y	Y	N
Standby-less system switchover (effects distributed) facility	Y	N	Y*

Legend:

Y: Can be used.

N: Cannot be used.

^* Only one HA group can be used at the switching destination.