RDF System Management Manual

Introducing RDF
HP NonStop RDF System Management Manual—524388-003
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Receiver Process
by the extractor, you will have to reinitialize RDF and resynchronize the primary and
backup databases.
In response to the UNPINAUDIT command, RDFCOM issues a prompt asking you to
confirm your request.
If the files are unpinned successfully, RDFCOM issues an informational message to
that effect.
If an error occurs while attempting to unpin the audit trail files, the command is ignored,
and RDFCOM issues a message indicating the error.
Receiver Process
A receiver process is a process pair that runs on the backup system. There is one
receiver for each configured extractor. A receiver process accepts audit records from
its extractor, sorts them, and then writes them to the appropriate RDF image trail, as
shown in Figure 1-6. (The restartability of a receiver ensures the receiver's correctness
at process takeover or under any conditions requiring resynchronization with its
extractor.)
A receiver determines which updater will apply the data, and sorts the data into the
image trail used by that updater. The records in the image trails are subsequently used
by updater processes to update the backup database.
Each receiver also creates image trail files, preallocates extents, and initiates rollovers.
Sorted Image Trails
RDF maintains its image data on disk volumes specified during RDF configuration. On
each of these volumes, the collection of files that contains image data is known as an
image trail; that is, there is one image trail per individual image trail volume.
The standard image trail used by RDF, called the master image trail, contains the
transaction status records that hold key information about whether a transaction has
committed or aborted. The master image trail is stored on the disk volume selected by
the master receiver’s RDFVOLUME configuration option. Note that you cannot
configure any updaters to the master image trail.
All updaters must be configured to secondary image trails. You can configure up to 255
secondary image trails in addition to the master image trail. Each secondary image trail
is stored on a separate volume, selected through the IMAGETRAIL configuration
option.
RDF uses multiple sorted image trails. With this feature, the receiver detects which
updaters are associated with which image trails. When it receives a record, the
receiver identifies the updater that will apply the record to the backup database. The
receiver then sorts the record into the appropriate image trail, and the record is written
to that image trail.