An Oracle instance is executing in a nondistributed configuration. The instance fails because of an operating system failure. Which background process would perform the instance recovery when the atabase is reopened ?
PMON
SMON
RECO
ARCn
CKPT
The System Monitor (SMON) process performs instance recovery at database startup when the database is reopened after an abnormal shutdown or failure. PMON cleans up failed user processes, and RECO resolves in-doubt distributed transactions.
To answer this question, you need to understand the role of the different background processes in an Oracle database.
Option A) PMON - PMON (Process Monitor) is responsible for process cleanup and process recovery. It is not involved in instance recovery.
Option B) SMON - SMON (System Monitor) is responsible for instance recovery. When an instance fails and is restarted, SMON performs crash recovery to bring the database to a consistent state.
Option C) RECO - RECO (Recoverer) is responsible for distributed transaction recovery. It is not involved in instance recovery.
Option D) ARCn - ARCn (Archiver) is responsible for archiving redo log files. It is not involved in instance recovery.
Option E) CKPT - CKPT (Checkpoint) is responsible for signaling the database writer (DBWn) to write dirty buffers to disk and update the checkpoint position in the control file. It is not involved in instance recovery.
The correct answer is B) SMON. SMON performs instance recovery when the database is reopened after an instance failure. It ensures that the database is brought to a consistent state by applying the necessary redo logs.
Therefore, the correct answer is B) SMON.