While your production database is running, take an (image copy)
backup and restore it on duplicate hardware. Note that an export will
not work!!!
On your standby database, issue the following commands:
ALTER DATABASE CREATE STANDBY CONTROLFILE AS 'filename';
ALTER DATABASE MOUNT STANDBY DATABASE;
RECOVER STANDBY DATABASE;
On systems prior to Oracle 8i, write a job to copy archived redo log
files from the primary database to the standby system, and apply the
redo log files to the standby database (pipe it). Remember the
database is recovering and will prompt you for the next log file to
apply.
Oracle 8i onwards provide an "Automated Standby Database" feature,
which will send archived, log files to the remote site via NET8, and
apply then to the standby database.
When one needs to activate the standby database, stop the recovery process and activate it:
ALTER DATABASE ACTIVATE STANDBY DATABASE;