Compaq AA-Q88CE-TE manual Controlling Transaction Replay, Rtruns32t newLimit

Partition Management

3.6 Managing Partitions

•rtr_partition_fail_to_shadow

•rtr_partition_pre32_compatible

3.6.6Controlling Transaction Replay

RTR has implemented the capability of controlling transaction replay in cases where a "killer message" happens during a transaction replay preventing recovery from continuing normally. A "killer message" presents a situation where server availability is lost because of the presence of a message capable of causing repeated server application failure during recovery. This is typically the result of an improperly handled condition or application programming error within the server itself. Under such circumstances it may be desirable to sidestep a particular transaction, maintain server operation, and manually process the transaction at some later time.

The RTR solution is to establish, for a given partition, the maximum number of retries for any given transaction presented during recovery. Once this limit has been exceeded, the offending transaction is removed from the recovery process and is written to the journal as an exception record. Subsequent processing of this transaction requires manual intervention by someone qualified to evaluate and correct the situation in both the application and in RTR. Once the application status is understood, the set transaction command can be used to update the journal, thus insuring that the final state of any manually transacted exceptions are accurately reflected in future recovery operations.

The recovery retry count indicates the maximum number of times that a transaction should be presented for recovery before being written to the journal as an exception. Once a transaction has been recorded as an exception, it is no longer considered eligible for recovery and requires manual processing by a qualified individual.

The recovery retry count is partition-specific, and applies to both local and shadow recovery operations. The default is no limit on the number of retries, which permits a killer message to bring down all available servers servicing a given partition.

The recovery retry count should be set before starting (or restarting) the application servers so that the limit is established prior to the start of recovery operations.

3.6.6.1 Command Line Example

RTR> SET PARTITION/RECOVERY_RETRY_COUNT=3 Facility1:Partition1

For more information on the SET PARTITION command see Chapter 6.

3.6.6.2 Programming Information

To set the partition transaction recovery limit, program the set_qualifier argument of rtr_set_info( ) as follows:

rtr_qualifier_value_t	set_qualifiers[ 2 ];
rtr_uns_32_t newLimit	= . . .;

set_qualifiers[ 0 ].qv_qualifier = rtr_partition_rcvy_retry_count; set_qualifiers[ 0 ].qv_value = &newLimit;

set_qualifiers[ 1 ].qv_qualifier = rtr_qualifiers_end; set_qualifiers[ 1 ].qv_value = NULL;

Partition Management 3–9