The rapid system switchover facility activates server processes and system servers in the HiRDB standby system in advance, instead of having to wait for them to be activated during system switchover. This facility reduces the system switchover time by the amount of time that is saved by not having to activate server processes and system servers during system switchover. For details about the rapid system switchover facility, see 26.7.7(2) Rapid system switchover facility.

In contrast to the standby system switchover facility that prepares a HiRDB standby system, it is not necessary to have a standby system when you use the standby-less system switchover facility. This facility transfers processing to another active unit instead of switching to a HiRDB standby system when an error occurs. This facility reduces the system switchover time by using an active unit.

When system switchover occurs in a unit with a back-end server or dictionary server, the back-end server or dictionary server cannot accept transactions until switchover is completed. This means that transactions processed by a back-end server or dictionary server that is involved in switchover result in an error.

The transaction queuing facility queues such transactions on the front-end server until system switchover is completed so that errors are not generated. This facility reduces transaction errors during system switchover. For details about the transaction queuing facility, see the following subsections:

• Standby system switchover (server mode): 26.7.10 Transaction queuing facility (for the rapid system switchover facility only)
• Standby-less system switchover (1:1): 26.8.8 Transaction queuing facility
• Standby-less system switchover (effects distributed): 26.9.8 Transaction queuing facility

Utilizing the transaction queuing facility during planned system switchover

You can use the pdtrnqing command to start transaction queuing. If you use the pdtrnqing command to start transaction queuing before carrying out planned system switchover, new transactions are queued even during planned system switchover. Therefore, executing a UAP during planned system switchover does not cause an error.

For details about planned system switchover using the transaction queuing facility, see the following subsections:

Standby system switchover (monitor mode): 26.6.2 Planned system switchover

Standby system switchover (server mode): 26.7.2 Planned system switchover

Standby-less system switchover (1:1): 26.8.2 Planned system switchover

Standby-less system switchover (effects distributed): 26.9.2 Planned system switchover