Introduction to Data Management

Protecting Databases With RDF
15873 Tandem Computers Incorporated 8-3
Features RDF offers the capabilities, benefits, and features described in the following
paragraphs.
Complete Backup at the
Remote Site
RDF allows users to maintain a current, complete, online copy of the database at the
backup node. Because this online, ready copy can be located far from the primary
system, RDF can minimize the effect of widescale disasters. If the primary site
becomes inaccessible or damaged, users can resume processing promptly at the
backup site, with minimal service disruption and data loss.
Resource for
Database Inquiries
In addition to backing up the primary database, the duplicate database maintained by
RDF can serve another purpose: an auxiliary resource for information retrieval.
Typically, the backup database supports this goal when you want to balance the
transaction workload by shifting several applications from a functioning primary site
to the backup site. Now, the backup database can become a read-only resource for the
transferred applications. You can use the backup database to:
Look up current data for inquiry purposes
Process heavy batch reporting loads
Consolidate data from multiple sites at a central site
Flexibility RDF has flexible disk requirements at the backup system. RDF does not require a
volume-to-volume relationship between the volumes on the primary system and
those on the backup system. For example, RDF can copy more than one audited
volume on the primary system to a single volume on the backup system, provided
that files are not partitioned. Also, backup volume names need not match primary
volume names.
Economic Use
of Resources
RDF conserves resources at both sites. On the primary system, RDF uses just two
processes to read, block, and transmit audit trail records to the backup system. On the
backup system, RDF checks and writes all records without using primary system
resources.
To reduce overhead on the EXPAND data communication lines, RDF blocks the audit
trail records before sending them to the backup system.
In addition, as mentioned earlier, RDF lets you balance the load between the primary
and backup systems to achieve greater processing efficiency.
Choice of Updating Modes RDF runs in two modes: online and archive. In the online mode, RDF applies
transactions to the backup database as soon as they arrive at the node. In the archive
mode, transactions are stored at the backup system and can be collectively applied
later.
Centralized Control
at Both Sites
RDF allows both the primary and secondary systems to protect each another. You
become owner and operator of the site where you are located. Thus, RDF lets you
maintain control of sensitive data without entrusting it to third parties for storage.
To control overall RDF operations, you enter commands to RDFCOM, a control utility
similar to TMFCOM that is used with TMF.