Home » Oracle » 1z0-058 » Which process will read the redo log of the failed Instance to Identify the database blocks that need to be recovered during the recovery process, after the reconfiguration of enqueue and cache part of Global Resource Directory (GRD)?
Your two-instance RAC database is running in ARCHIVELOG mode. The instance running on node1 fails and this failure is detected by the instance running on node2, which initiates the recovery process for node1.
Which process will read the redo log of the failed Instance to Identify the database blocks that need to be recovered during the recovery process, after the reconfiguration of enqueue and cache part of Global Resource Directory (GRD)?
A. PMON
B. MMON
C. SMON
D. GES
E. GCS
Correct Answer: C
Explanation/Reference:
Instance Recovery and Database Availability
The graphic illustrates the degree of database availability during each step of Oracle instance recovery:
1. Real Application Clusters is running on multiple nodes.
2. Node failure is detected.
3. The enqueue part of the GRD is reconfigured; resource management is redistributed to the surviving nodes. This operation occurs relatively quickly.
4. The cache part of the GRD is reconfigured and SMON reads the redo log of the failed instance to identify the database blocks that it needs to recover.
5. SMON issues the GRD requests to obtain all the database blocks it needs for recovery. After the requests are complete, all other blocks are accessible.
6. The Oracle server performs roll forward recovery. Redo logs of the failed threads are applied to the database, and blocks are available right after their recovery is completed.
7. The Oracle server performs rollback recovery. Undo blocks are applied to the database for all uncommitted transactions.
8. Instance recovery is complete and all data is accessible.
Note: The dashed line represents the blocks identified in step 2 in the previous slide. Also, the dotted steps represent the ones identified in the previous slide.
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