Database backup and recovery
No matter how much data security you build up there will always be situations where the database crashes or any other failure occurs.
In that case we always lie in the middle of a situation where it happens where we actually need the requirement of a recovery manager or a software or tool which can recover the lost information.
For discovering the recovery methods firstly we need to understand the threats that can lead us to such a situation:-
They are as follows:-
Instance failure In this case the Oracle while running as a program crashes for which the database instance needs to be restarted.
Losing files It is one of the most serious threats where some of the most important files in the code tree are lost. It is advised to make the code tree as a part of the backup.
Dropped objects There are some objects in the database which are dropped by mistake and can lead to a serious problem in the database due to the same.
Corruption
It is one of the most risky threats which can cause damage to the information. In this the rows in the database becomes unreadable and cannot be interpreted.
It can be :-
1)Physical-loss in sectors in disks
2)Logical-Data is missing or unreadable
3)Corrupted data
Recovery using RMAN(Recovery Manager)
- Fig 9.3
As shown by the figure 9.3 the Recovery manager is launched which is a tool which is meant for recovering lost files and it an alternative to the enterprise backup utility (EBU) tool and was launched along with Oracle 8i.
It can be launched directly from the command line as shown in fig 9.3
One launched we can connect to the target and setup a recovery plan for the same as shown in the Fig 9.5
- Fig 9.4
The above figure shows that the RMAN is launched and is ready to take up the backup and restore the file lost.
Fig 9.5 shows that the target database where the backup needs to be taken is connected to.
Fig 9.6 shows how the password is required when the database target is connected to.
- Fig 9.5
- Fig 9.6
The above figure shows that the RMAN is connected to a target database which when launched requires a password for the authentication.