Was it Einstein who once said "Things should be as complex as they need to be, but no more ..."?
Dbvisit - Oracle Standby Database Solution within your reach
What is a standby database?
A Standby Database is a shadow copy of an operational or primary database on a remote or local* server.
It protects agains data loss and availability of the primary database.
A standby database is synchronised with the primary database on a continual basis and
can be used for disaster recovery, backups, replication, analysis, shadow environment, high availability and reporting
to name a few applications.
A standby database is far superior to a normal backup as it is instantly available in the event of a disaster or failure.
To restore a backup takes time, and during the restore time the system is not available.
The restore may also cause too much impact on other systems. The hardware may also not be available for the restore causing further delay.
With a standby database there is nothing to restore in the event of a failure as the standby database is always available, up to date and ready to take over.
It is possible to switch applications over to the standby database in a matter of minutes to allow business continuity.
Overview of standby database:
- Exact copy of main database in a remote or local* location.
- Is held up to date by applying changes from main database.
- In the event of a disaster, standby database becomes active.
- Users (or applications) are transferred to standby database to continue operation.
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Technical overview of standby database: (see picture below)
- Database updates are captured in redo logs.
- Updates in redo logs are not permanent. They get overwritten, as there is a set number of redo logs and they written to in a cyclic fashion (when the last one is full, the first one is used again).
- A copy is made of the redo log which is then called an archive log. This is a permanent copy.
- The archive log is transferred to the standby server.
- The transferred archive logs are applied to the standby database.
- Standby database is up to date with primary database.
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Dbvisit manages the whole process of replicating the logs to the standby database and ensures they are applied to the standby database
so that the standby database is fully up to date.
When disaster strikes and you lose your primary database, your business can continue to operate as you switch over to the standby database.
Dbvisit manages the process with these unique features:
- Supports Oracle versions 8 to 11g, both 32 bit and 64 bit.
- Compresses archive logs before replicating, saving bandwidth.
- Uses standard ssh (22) or rsh (23) network ports to transfer logs.
- Runs as stand-alone software outside the database, not impacting database performance.
- Uses checksum to ensure Oracle logs have transferred correctly.
- Automatically recovers from network outages.
- Automatic graceful switchover (also referred to as role reversal) which may be used for planned outages. The primary database transitions to a standby database and the standby database transitions to a primary database with no data loss. Graceful switchover works for Oracle 8i, 9i, 10g and 11g.
- Oracle RAC support. Dbvisit support Oracle Real Application Cluster.
- Automatic space management. Dbvisit will automatically add new datafiles and tablespaces to the standby database which have been added to the primary database.
- Multiple Standby Databases from the same primary database. For example one standby database can be used for DR and another standby can be used for running large reports without impacting the primary database.
- Automatic notification included. Notification thresholds can be set.
Dbvisit is the complete Oracle disaster recovery software to allow business continuity in an emergency or failure.
*A standby database in the same location as the primary server should not be used for disaster recovery but for reporting, high availability, shadow environment or analysis purposes only.
Dbvisit is a registered trademark of Avisit Solutions Limited
Oracle is a registered trademark of Oracle Corporation
