What Is The Database Disaster Oracle Recovery?

Created by Larry Ellison, Ed Oates and Bob Miner, the Software Development Laboratories in 1977
developed the original Oracle DBMS (or Database Management System.) The name Oracle is derived
from the code of a project that they worked on at Ampex. Software Development Laboratories was then
renamed to Relational Software Inc. (or RSI) in 1979 – which was later named Oracle Corporation in the
year 1984.

The two major components of an Oracle DBMS are Database and Instance. The Database contains all
the control files; redo logs (that contain your data and Oracle metadata), and physical data files. The
control files contain Oracle metadata which are very important and contain all the information that is
needed to access the database. The redo log holds records for any changes that have been done.

An Instance, however, is a combination of the background processes and the pool of physical memory
called RAM allocated to Oracle. The RAM is also called System Global Area (or SGA.) The RAM is
employed to cache data (since the RAM is a thousand times faster than I/O.)

There are different types of backups, namely: whole Database Backup, Consistent Whole Database
Backup, Inconsistent Whole Database, Inconsistent Closed Backups, Tablespace Backups, Datafile
Backups, and Control File Backups. Each backup differs the others, and knowing which backup method
should be used is essential.

RMAN (or recovery manager) is a component that establishes a connection with a particular server
process. The RMAN automates the flow of data for recovery operations and backup. The OS (or
Operating System) is another process but one where the database is backed up manually by a specific
command execution to certain user specifications. The Oracle export Utility, however, makes backup
logical by writing data from the Oracle database to OS files. The Oracle Enterprise Manager, on the other
hand, runs with a GUI interface that brings Recovery Manager to work.


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