RDF System Management Manual for J-series and H-series RVUs (RDF 1.10)

• A NonStop SQL/MP DDL operation using the WITH SHARED ACCESS option is detected
• An exception record is written
You can peruse messages in the EMS log on your terminal screen by using Viewpoint or whatever
other tool you normally use for monitoring $0. When you do that, you are dealing with the entire
EMS log (not just RDF messages).
To isolate RDF messages from the rest of the EMS log, you can use the supplied EMS filter RDFFLTO
with an EMS printing distributor to produce an intermediate entry-sequenced file that you then can
scan using the RDFSCAN utility.
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 Chapter 9 (page 250).
RDF 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 records from the TMF MAT and,
optionally, from auxiliary audit trails.
• On the primary system, the extractor process filters out audit records that are not relevant to
the backup database (audit records for volumes or files not protected by RDF) and then transmits
the relevant audit records to the backup system. These audit records have additional information
added to them by the extractor and the transformed audit records are then called image
records.
• On the backup system, the receiver process accepts the buffer of image records sent by the
extractor, sorts each record to the correct image trail buffer, and eventually writes the collection
of image trail buffers to the actual image trailson disk.
• On the backup system, each updater process reads the image records it is responsible for out
of its image trail and sends the audit portion directly to disk process that manages the volume
where that updater's database files reside. During normal RDF operations, the disk process
applies the audit to the affected database file or table with the logical REDO operation. During
the special RDF Takeover or stop-update-to-time operations, the disk process can also perform
logical UNDO operations for those audit records that need to be backed out of the backup
database.
NOTE: Throughout this manual, the terms image records and audit records are used
interchangeably on the backup system. An image record is just the original audit record with some
additional RDF specific information added to it. When an updater prepares an image record to
send to the disk process, it strips out that added RDF information and sends the original audit
record.
Figure 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 in “RDF
Operations”.
34 Introducing RDF