RDF System Management Manual

Introducing RDF
HP NonStop RDF System Management Manual—524388-003
1-23
Updater Processes
Audited Database Files
All database files on the backup system are audited files.
Each updater maintains a file status table to keep track of the files it has open. An
updater closes any database file that has not been updated recently. Updaters also
close database files when a STOP RDF or STOP UPDATE command is issued, or
when the updater restarts because of error conditions.
An updater process can have up to 500 files open simultaneously. When it has the
maximum number of files open and needs to open another file, it first determines if
there are any files that have not been accessed recently and closes just them; if all of
the open files have been accessed recently, then the updater closes all of them before
it continues processing. For the SMF ramifications of this file limit see the note under
Using SMF With RDF in Section 2.
UNDO Pass
Updaters perform an UNDO pass over the image trail during final processing of RDF
takeover and stop-update-to-time operations. This is because data already applied to
the backup database must be undone if the associated transaction(s) did not commit
prior to the start of the takeover operation or prior to the specified timestamp.
For takeover operations there are three phases of undo: local undo, file undo (if file-
incompletes from the primary system are still unresolved), and network undo (if you are
operating in an RDF network). For stop-update-to-time operations there is only local
undo (file-incompletes cause abend, and network undo is not supported).
Restart Information
RDF has a CONTEXT file in which each updater process maintains a context record. A
context record specifies the position (referred to as the restart position) in the image
trail where the updater was at the last context save point. All data for the associated
data volume in the backup database prior to the specified restart position is safe on
disk (has been applied to the backup database).
If an updater detects a restartable error, it restarts. Upon being restarted, an updater
reads its context record and restarts processing in the image trail at the specified
restart position.
Partitioned Files, Alternate Key Files, and Indexes
Each updater is responsible for applying audit data to partitions corresponding to the
volume on the primary system that updater is protecting. Updates are applied directly
to the specific partition, regardless of whether it is a primary or secondary partition.
RDF does not use the file system for partition mapping.
Furthermore, because updates to the backup database are applied by logical
REDO/UNDO operations, alternate key files and NonStop SQL/MP and NonStop
SQL/MX indexes are not affected by an update to a file or table. Alternate key files or