RDF/IMP and IMPX System Management Manual (RDF 1.4+)

Introducing RDF

HP NonStop RDF/IMP and IMPX System Management Manual—524388-001

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Support for Network Transactions

The RDF/IMPX product supports network transactions: transactions that update data

residing on more than one RDF primary system.

More specifically, the updates for a transaction on one of the two primary systems may

have been successfully transmitted and applied to the associated backup database,

but a disaster brought down the other primary system before the updates by the

transaction on that system could be sent to its backup database. After executing RDF

takeover operations on both backup systems, the data from the network transaction

would be present in one backup database but not in the one brought down by the

disaster. Thus the distributed backup database is inconsistent with regard to the

affected network transaction.

For information about this capability, see Section 13, Network Transactions.

Lockstep Operation

Lockstep operation, which is available with the RDF/IMPX product, prevents an

application from executing further processing based on a committed business

transaction until all audit associated with that transaction is safely stored in the image

trails on the backup system.

This is accomplished by means of a new procedure, named DoLockstep, that you call

immediately after calling endtransaction. With this lockstep protocol, the business

transaction is actually committed on the primary system prior to the start of the

DoLockstep operation, but the application is not allowed to continue processing until

DoLockstep has returned status to the application.

For information about this capability, see Section 14, Lockstep Operation.

Monitoring RDF Entities With ASAP

ASAP (HP NonStop Availability Stats and Performance) allows many different

subsystem entities to be monitored across a network of HP NonStop servers. The

status and statistics for the entities are collected on a single system, and are then

monitored either through the ASAP command interface or through the ASAP graphical

user interface PC client.