| Data saved in the Oracle database components is | | | | Cause |
| saved in hierarchical format and at four different | | | | The root cause for the occurrence of the above error |
| levels-Tablespace, Segments, Extents, and Blocks. | | | | message is corruption in UNDO tablespace. |
| Corruption at any level results in unmountability of your | | | | Resolution |
| database, further resulting in inaccessibility of database | | | | To get past the above error message and to access |
| records. The most common level at which corruption | | | | the database records, you need to take underneath |
| occurs is at initial level (Tablespace). Few main | | | | actions: |
| reasons for corruption could be improper system | | | | Change the value of undo_management parameter to |
| shutdown, simultaneous modification, and human | | | | 'MANUAL'. The default value for this parameter is |
| mistakes. In order to overcome a tablespace | | | | 'AUTO'. |
| corruption scenario, restore the database from a | | | | Create a new UNDO tablespace and drop the |
| 'standby database'. However, if no backup of your | | | | corrupted tablespace. |
| database exists or backup itself is corrupted, then you | | | | In most cases the 'Instance' gets started after |
| will need to repair the logically damaged database | | | | following the above steps. However, if the database |
| using advanced third-party Oracle Database | | | | remains unmountable and you encounter the above |
| Recovery application. | | | | error message, then follow the below measures: |
| To explain the above scenario, consider the below | | | | Use a Standby database and perform restoration. |
| error message: | | | | However, in case of absence of a valid backup, use a |
| "ORA-00376: file xx cannot be read at this time" | | | | powerful oracle database repair software. Such |
| The above error message appears at the time of | | | | Oracle Recovery tools use powerful recovery |
| mounting your database. After the above error | | | | mechanisms to repair every corrupted database, |
| message pops up, the database records become | | | | regardless of its cause of corruption. The read only |
| inaccessible. Furthermore, the same error message | | | | software is competent enough to recover all Oracle |
| pops up every time you try to mount your database. | | | | database objects like tablespace, tables, and triggers. |