RDF System Management Manual

Installing and Configuring RDF
HP NonStop RDF System Management Manual—524388-003
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Initializating RDF Without Stopping TMF
Initializating RDF Without Stopping TMF
The INITIALIZE RDF command includes a parameter, INITTIME inittime , that you
can use to initialize the RDF product without stopping TMF or your applications.
There are two cases where you would use this capability:
1. If you want to install a new version of the RDF product and you cannot afford to
stop TMF even momentarily to get a TMF shutdown timestamp.
2. If you are running RDF and encounter a problem for which you would like to
reinitialize it without having to resynchronize your databases.
Determining a Valid inittime Value
When using the INITTIME parameter without the NOW clause, it is important that you
specify a valid inittime value.
To do so, first issue a STATUS RDF command and take note of the highest updater
RTD time. Then round that RTD time up to the next higher minute (0:43 becomes 1:00,
1:27 becomes 2:00, 3:04 becomes 4:00, and so forth). Finally, subtract that rounded-
up time from the current system time shown in the status display.
inittime := (current-system-time — rounded-highest-updater-RTD-time)
RDFCOM then subtracts an additional three minutes from the specified timestamp.
This is to ensure that the extractor’s starting position is at a point in the MAT where
RDF had previously sent audit information to the backup system and the updaters had
applied it to the backup database. This practice guarantees that no audit information
will be lost during initialization.
When you include the INITTIME parameter in the INITIALIZE RDF command,
RDFCOM initiates a backward scan of the MAT searching for the first commit or abort
record whose timestamp is less than the specified inittime . When RDF is
subsequently restarted, some of the audit information will be reapplied to the backup
database. This does not cause any inconsistencies between the primary and backup
databases, but rather ensures that they stay completely synchronized with one
another.
The NOW clause of the INITTIME parameter causes RDF to be initialized at the
current date and time. The NOW clause simplifies initialization and configuration of a
reverse RDF environment created in response to a reverse trigger. See the Example
under the description of the SET TRIGGER command.
Special Considerations
When using this form of the INITIALIZE RDF command, there are three special cases
which you might encounter.