25.1.3 Application criteria for the system switchover facilities

Organization of this subsection
(1) Application criteria
(2) Usability of each system switchover facility when another system switchover facility is already being used

(1) Application criteria

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

Table 25-5 System switchover facility application criteria

ImportanceStandby system switchover facilityStandby-less system switchover (1:1) facilityStandby-less system switchover (effects distributed) facility
Transaction performanceBestPoorGood
  • 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 requirementPoorBestBest
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 errorsBestPoorBest
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.

(2) Usability of each system switchover facility when another system switchover facility is already being used

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 usedUsability of the standby system switchover facilityUsability of the standby-less system switchover (1:1) facilityUsability of the standby-less system switchover (effects distributed) facility
Standby system switchover facilityYYY
Standby-less system switchover (1:1) facilityYYN
Standby-less system switchover (effects distributed) facilityYNY*
Legend:
Y: Can be used.
N: Cannot be used.
* Only one HA group can be used at the switching destination.