Given below is a list of scenarios:
1) A user terminates his session abnormally.
2) The connection between the server and the client application terminates because of a
network failure.
3) A schema is accidentally dropped.
4) The tablespace is accidentally dropped from the database.
5) The hard disk gets corrupted and the data files in the disk are lost.
6) The database instance abnormally shuts down because of power failure.
Which scenarios require DBA intervention to perform recovery?
A.
1, 3, and 6
B.
4, 5, and 6
C.
3, 4, and 5
D.
1, 2, and 6
A user error and media failures require DBA perform recovery.
1. User abort their session, belonging to the user process fails. With the exception disconnected user process instance may contain ongoing need rollback uncommitted tasks. In order to ensure that the server processes the session remain connected, Process Monitor (PMON) background process periodically polls the server process. If a user PMON discovery server process is no longer connected, PMON will recover from any ongoing transaction processing; will roll back uncommitted changes and release any locks held by the failed session. DBA is not required when a user process fails to recover from the intervention, but the administrator must watch the trends.
2. The connection between the server and the client application due to a network failure ended. It belongs to a network failure. The best solution is to provide a network fault redundant path for the network connection. By backing up the listener, network connections and network interface cards can reduce the chances of network failure, and thus avoid affecting system availability. DBA does not need to perform the restore.
3. accidentally delete schema, belonging to user errors. DBA needs to perform recovery. The user may inadvertently delete or modify data. If you do not submit or withdraw their program, you can simply roll back.
You can query the online redo logs and archived redo logs through Enterprise Manager or SQL interface Oracle LogMiner. Transaction data retention time in the online redo log may be longer than the retention time in the reduction stage, if configured for archiving redo information, before you delete the archive will remain redo information. Flash back to the table by the state deleted before the user can delete the table after table recovery from the recycle bin. If you clear the Recycle Bin, or user PURGE option to delete the table, then the database is configured under the right circumstances, it can still be restored (PITR) by using the point in time to recover deleted tables.
4. accidentally deleted from the database table space, belong to user errors. DBA needs to perform recovery. Same reason 3
5. damaged hard disk and data files are missing. Belong to a media failure, the DBA perform recovery. The media failure is defined as a result of one or more database files (data files, control files or redo log file) any failure lost or damaged. Recover from a media failure, need to restore and recover the missing files. To ensure that the database can recover from a media failure.
6. The database instance shuts down unexpectedly because of power outages. Belong instance failure, without DBA intervention.
Schematic drop, TB drop, file lost
6. THE DB SHUTS DOWN B/C OF POWER FAILURE. User can turn back on.
Also this is not within DBA’s control (power outage)