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

Network Transactions
Compaq NonStop™ RDF/IMP and IMPX System Management Manual—522204-001
13-13
RDF Networks and Stop-Update-to-Timestamp
Operations
RDF Networks and Stop-Update-to-Timestamp
Operations
Stop-update-to-timestamp operations affect only the backup database of the particular
system on which they are initiated. If you have an RDF network, you can execute a
stop-update-to-timestamp operation on any primary system in the network, but the
operation affects only the backup database of the system on which it is initiated (it does
not affect data in any other backup database, even for network transactions).
For example, suppose you have ten RDF subsystems in your RDF network, and most
transactions on each system touch two or more systems in the network. Thus, nearly
every transaction is a network transaction. If you execute a stop-update-to-timestamp
operation on one of these systems, that operation only brings that particular subsystem’s
backup database into a consistent state with regard to transaction commit times on the
associated primary database. It does not execute undo operations on any other backup
systems in the RDF network.
To illustrate this, assume you began a transaction (T
10
) at 12:00 P.M., executed ten
updates on each of two primary systems in an RDF network (\A and \B), and committed
T
10
at 12:05. Assume further that you had previously issued a stop-update-to-timestamp
operation on system \A, specifying 12:01 P.M. When the stop-update-to-timestamp
operation completes, the data for T
10
is backed out of system \A’s backup database
because T
10
committed after 12:00 P.M. The data for T
10
on system \B’s backup
database, however, remains unaffected (because a stop-update-to-timestamp operation
only applies to the backup system associated with the primary system on which it is
initiated).
Note also that it is rare for clocks on different systems to have exactly the same values,
thus rendering stop-update-to-timestamp operations impossible to perform correctly
across multiple backup systems.
Sample Configurations
Two sample configurations follow, one for the network master and one for a non
network master. The new attributes are highlighted in bold.
Sample Network Master Configuration
The configuration that follows is for a network master RDF subsystem running from
\RDF04 to \RDF06:
SET RDF SOFTWARELOC $SYSTEM.RDF
SET RDF BACKUPSWAP $SWAP01
SET RDF LOGDEVICE $0
SET RDF LOGFILE $0
SET RDF PRIMARYSWAP $SWAP01
SET RDF UPDATERDELAY 10
SET RDF UPDATERTXTIME 60
SET RDF UPDATERRTDWARNING 60
SET RDF UPDATEROPEN PROTECTED
SET RDF NETWORK ON