RDF System Management Manual for H-Series RVUs (RDF 1.8)

• The monitor detects the unexpected termination of any RDF process and sends out abort
RDF messages.
• You perform a NonStop SQL/MP and NonStop SQL/MX DDL operation on the primary
system that includes the WITH SHARED ACCESS option. For more information, see
“Performing Shared Access DDL Operations” (page 142).
• A takeover operation completes on the RDF backup system.
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 in “Using SMF With RDF” (page 70).
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 NonStop SQL/MP and NonStop
SQL/MX indexes are updated independently as a consequence of the individual audit records
generated on the primary system by TMF software.
RDF Operations 53