RDF/IMP and IMPX System Management Manual (RDF 1.3+)

Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001

13-1

Network Transactions

Starting with version 1, update 2, the RDF/IMPX product is able to guarantee backup

database consistency for transactions that update data residing on more than one RDF

primary system.

In the past you could execute such transactions, but the RDF product could not

guarantee database consistency among the associated backup systems following the

failure of one of the primary systems.

This new capability requires two major external changes.

1. If you have a distributed database spread over several RDF primary systems, you

must configure an RDF network wherein each primary system has its own RDF

subsystem that replicates its local data to its own backup system. This is referred to

as an RDF network because each RDF subsystem knows the names of the systems

protected by all other RDF subsystems in the network. One, and only one, RDF

subsystem within the network must be configured as the network master.

2. If you lose one or more RDF primary systems in the RDF network, you must

execute RDF takeover operations on all backup systems in the network.

For those primary systems still alive, you must first quiesce all application activity

(both local and remote) so that no further database updates are being performed, and

then bring down the communication lines between the primary and backup systems

before initiating the takeover.

With the introduction of network transaction support, you must now be more careful

when creating Enscribe files that have alternate key files. Specifically, when you create

an Enscribe file with an altkey file you must ensure that both files reside on the same

primary system and that both are protected by the same RDF subsystem. If you do not

do so, then the updater responsible for creating the file on the backup system will not

create the file; rather, it will report an error 740 when it determines that the altkey file is

not protected by its RDF subsystem.

Note. This capability is currently not supported in conjunction with the triple contingency

feature. Furthermore, it is strongly recommended that all databases that might be touched by

a network transaction be protected by the RDF/IMPX product.