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

Introducing RDF
HP NonStop RDF/IMP and IMPX System Management Manual—524388-001
1-11
Tasks
Using RDFSCAN commands, you can specify:
•
A starting point for scanning the intermediate RDF message file
•
How many records to scan
•
Text to search for in the file
Tasks and examples for using RDFSCAN commands appear throughout the manual.
Reference information for all commands appears in Section 9, Entering RDFSCAN
Commands.
Tasks
To maintain a duplicate of the primary database on the backup system, RDF performs
four fundamental tasks:
•
On the primary system, the extractor process captures audit information from the
TMF MAT and, optionally, from auxiliary audit trails.
•
On the primary system, the extractor process filters out audit information that is not
relevant to the backup database (audit information for volumes or files not
protected by RDF) and then transmits the relevant audit information to the backup
system. These records on the backup system are called image records.
•
On the backup system, the receiver process accepts the filtered audit information,
sorts it, and then writes it to the appropriate RDF image trail.
•
On the backup system, updater processes read the records from their image trail
files and pass them to the disk process. The disk process interprets them and
performs the logical REDO operation for each record, updating rows or records in
the backup database.
Figure 1-3
illustrates these tasks as they are performed during normal processing
when RDF updating is enabled. The sequence of events differs when updating is
disabled, as explained under RDF Operations
.