Compaq AA-Q88CE-TE manual Controlling Recovery, Example usage of the qualifiers

Partition Management

3.6 Managing Partitions

3.6.2 Controlling Transaction Presentation

Transaction presentation is the process of passing transactions to idle server channels for processing. While transaction presentation is active, new transactions are started on the first free server channel for the appropriate partition.

Use the /SUSPEND qualifier to the SET PARTITION command to halt the presentation of new transactions to servers on the backend where the command is entered. The command completes when the processing of all currently active transactions is complete. The optional /TIMEOUT qualifier specifies, as a number of seconds, the time that the command waits for completion. If the command times out, presentation of new transactions are suspended, but there still exist transactions for which servers have yet to complete processing. The operator must decide either to reenter the command and wait a further period of time, or resume the partition. Note that use of this command does not affect any transaction timeout value specified by RTR clients, so such transactions may encounter a timeout condition if the partition remains suspended.

/RESUME qualifier restarts presentation of transactions to the server application channels.

3.6.2.1 Command Line Example

Example usage of the qualifiers:

RTR> SET PARTITION/FACILITY=Facility1/SUSPEND/TIMEOUT=5 Facility1:Partition1

RTR>

RTR> SET PARTITION/FACILITY=Facility1/RESUME Facility1:Partition1

For a more complete description see the SET PARTITION command in Chapter 6.

3.6.2.2 Programming Information

To suspend transaction presentation on a partition with a timeout of 30 seconds, program the set_qualifier argument of the rtr_set_info( ) call as follows:

rtr_qualifier_value_t	set_qualifiers[ 3 ];
rtr_partition_state_t	newState = rtr_partition_state_suspend;

rtr_uns_32_t ulTimeoutSecs = 30;

set_qualifiers[ 0 ].qv_qualifier = rtr_partition_state; set_qualifiers[ 0 ].qv_value = &newState;

set_qualifiers[ 1 ].qv_qualifier = rtr_partition_cmd_timeout_secs; set_qualifiers[ 1 ].qv_value = &ulTimeoutSecs; set_qualifiers[ 2 ].qv_qualifier = rtr_qualifiers_end; set_qualifiers[ 2 ].qv_value = NULL;

Note that the timeout is an optional element. To resume transaction presentation, specify newState as rtr_partition_state_resume.

3.6.3 Controlling Recovery

The purpose of RTR automated recovery is to ensure the best possible consistency of application databases across a distributed computing environment. To achieve this RTR relies in part on information stored in the journals of the participating systems. Should one or more of these systems be unavailable at recovery time, automated recovery may stall or fail awaiting availability of these systems and their journals. This is good from the point of view of data consistency, but bad when viewed from an application availability perspective.

3–6Partition Management