The Hot Standby option is a discrete, separately-purchasable
Oracle product that provides high-performance database
replication. The Hot Standby option prevents your Oracle Rdb
database or Oracle CODASYL DBMS database from becoming a single
point of failure by physically duplicating the database at a
geographically remote-standby site. In the event of a node
or cluster failure, the replicated "hot standby" database
automatically becomes the master database and takes over
application processing.
The Hot Standby option automatically performs coordinated
database synchronization with high performance and minimal impact
on system resources. You need to intervene manually only to start
the replication services, and to fail over applications to the
hot standby database if a failure occurs. The Hot Standby option
does not require specific hardware to operate, and you do not
need to make any changes to application coding.
You start the replication operation by entering a Replicate
command using either the Oracle RMU or DBO utility, as
appropriate. These utilities provide syntax and semantics for
the following Replicate commands:
o Replicate After_Journal Configure-automatically sets up
replication attributes for the master and standby databases
o Replicate After_Journal Reopen_Output-allows you to view a
replication output file
o Replicate After_Journal Start-initiates replication operations
on the master node or the standby node
o Replicate After_Journal Stop-terminates replication operations
on the node where you enter the command
Once started, the replication operation automates the AIJ
backup and rollforward operations. The standby database is
created from a backup copy of the master database. As database
modifications are applied to the after-image journal for the
master database, the Hot Standby option automatically applies the
modification over a high-speed network connection to the after-
image journal for the standby database. Although, the primary
purpose of database replication is to provide a higher degree of
availability for mission-critical systems, the standby database
can also serve as a read-only database for offline generation of
reports.
The Hot Standby option is completely compatible with the standard
Oracle Rdb and CODASYL DBMS database components. The master and
standby databases can be implemented on systems running OpenVMS
Alpha or OpenVMS I64, or any combination of these operating
systems. For example, you can use the Hot Standby option to
replicate a master database running on OpenVMS Alpha to a standby
database running on OpenVMS I64. The only requirement is that the
network connection is common to both operating system platforms.
For additional information, see the Hot_Standby Help topic in the
command line help for RMU.
Refer to the Oracle Rdb7 and Oracle CODASYL DBMS: Guide to Hot
Standby Databases for information about the Hot Standby option.