You must apply the standby-less system switchover (effects distributed) facility. For details about this facility, see 26. Using the System Switchover Facility.

Select whether the transaction queuing facility is to be applied. Guidelines on applying this facility are provided below. For details about the transaction queuing facility, see the following subsections:

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

(a) Processing method when the transaction queuing facility is used

The processing method when the transaction queuing facility is used is explained below.

Processing method

1. When a back-end server is migrated, startups of new transactions for that back-end server are put on hold.
2. Waits for termination of transactions being processed by the back-end server that is to be migrated. When there are no more transactions being processed by the back-end server to be migrated, the back-end server is migrated.
3. Transactions put on hold in 1 are started.

Note that you can specify the transaction queuing wait time in the pd_ha_trn_queuing_wait_time operand. If termination of a back-end server is delayed for a considerable period because of a transaction that requires a long time to execute, transaction queuing is cancelled when the transaction queuing wait time is exceeded and migration of the back-end server is cancelled. In such a case, the transactions that were placed on hold in 1 are restarted.

(b) Processing method when the transaction queuing facility is not used

A back-end server is migrated without placing startups of new transactions on hold and without waiting for transactions currently executing to terminate.

(c) Advantages and disadvantages of the transaction queuing facility

The following table shows the advantages and disadvantages of the transaction queuing facility.

Table 11-1 Advantages and disadvantages of the transaction queuing facility

Application of the transaction queuing facility	Advantages	Disadvantages
Applied	Transaction errors can be avoided during back-end server migration (except when back-end server startup takes a long time).	Transactions can become queued during back-end server migration. Back-end server migration can take longer than when the transaction queuing facility is not applied. Back-end server migration might be cancelled if there is a transaction that executes over an extended period.
Not applied	Transactions are not queued during back-end server migration. A back-end server can be migrated even when there is a transaction that executes over an extended period. Back-end server migration takes less time than when the transaction queuing facility is applied.	A transaction that is executing at the time of back-end server migration terminates with an error. A transaction that starts during back-end server migration terminates with an error.

Reference note

Because the transaction queuing facility is also used for the system switchover at the time of system failure, you might want to consider using this facility together with the system switchover facility.

(d) Setting up the transaction queuing facility

To use the transaction queuing facility, you must specify queuing in the pd_ha_transaction operand.

You must also specify the sum of the times described below as the transaction queuing wait time in the pd_ha_trn_queuing_wait_time operand.

• Maximum queuing time for transactions that occur during back-end server migration
• Time in the back-end server migration scenario between forced server termination (which basically is the time at which the KFPS01843-I message is output when the pdstop -s -f command is entered) and completion of server startup (issuance of the KFPS01813-I message)

If the transaction queuing facility is not used, specify error in the pd_ha_transaction operand or omit this operand.