| A database administrator performs various operations | | | | 'shutdown immediate' command and change the |
| (performing incremental backups, identifying and | | | | datafile with its 'alive' copy. |
| resolving network issues, viewing archive log | | | | After this, when you try to mount your Oracle |
| destination, error generation in alert log, and more) to | | | | database, it does not mount. |
| ensure that the database always remains in a running | | | | Cause: |
| state. However, the possibility of database corruption | | | | The fundamental reason for unmountability of the |
| exists due to human mistakes, virus attacks, and | | | | database is corruption in datafile. To prevent the |
| hardware corruption. In most cases, the database | | | | corruption of datafile, you should never follow the |
| remains unmountable after it is corrupted, further | | | | above steps sequentially. |
| rendering to inaccessibility of all its records. In such | | | | Resolution: |
| situations, if the administrator wants to access the | | | | To resolve datafile corruption and to mount your |
| Oracle records, then s/he will need to use a cold | | | | Oracle database, it is advisable to restore the |
| backup to restore the database. However, if the | | | | database from a standby database. However, if no |
| administrator has not created any backup or the | | | | such database exists, then you will need to repair the |
| backup is not sufficient to meet all her/his | | | | database. To effectively do so, you will need to |
| requirements, then s/he needs to use an advanced | | | | search for a commercial DBF recovery application that |
| third-party Oracle Recovery utility to repair the | | | | can repair your corrupted database. |
| database. | | | | A repair tool to recover Oracle and to bring it back to |
| Consider a practical case, where you, as a database | | | | a reusable state can be easily downloaded from the |
| administrator, perform below steps: | | | | Internet. Such tools can Recover Oracle after any |
| 1.You copy your database file when your database is | | | | logical corruption scenario using powerful recovery |
| alive. | | | | algorithms. Moreover, these tools do not make any |
| 2.Then, you update the table stored in the data file. | | | | change in the original database, making them |
| 3.After this, you shutdown the database using | | | | completely non-destructive in nature. |