Standby database
A standby database is a current copy of a productive database on a second, mostly remote computer system. Standby databases are mostly used to increase reliability .
Background backup
A standby database is kept up to date by so-called log shipping. The transaction log of the so-called primary database is transferred to the standby system and traced there. All transactions that were carried out on the primary database are traced by transferring the transaction log on the standby system. The standby database is therefore at the same level as the primary database with a slight time lag and therefore contains the same data.
Resilience
A (primary) database and its standby database together form a failover cluster . The entire system should be fault-tolerant and highly available . If the primary database fails, users can continue working with the standby database. Transactions running on the standby database must later be transferred back to the primary database. Even if the primary database is accidentally deleted, the standby database can be reloaded onto the computer.
Product and service market
The manufacturers of Sybase , Oracle ( Oracle Dataguard ), Informix , Microsoft and DB2 offer options for standby databases . Alternatively, there are also other providers who offer administration and operation of standby databases, even in heterogeneous database landscapes.
See also
literature
- Andrea Held: Oracle 10g high availability. The fail-safe database with Real Application Cluster (RAC), Data Guard and Flashback . Addison-Wesley, Munich 2005, ISBN 3-8273-2163-8 .
- Bipul Kumar: Oracle Data Guard: Standby Database Failover Handbook . Rampant Techpress, 2005, ISBN 0-9745993-8-7 (English).