What causes Node eviction in Oracle RAC?

What is node eviction?

Node eviction in RAC is done when a heartbeat indicates that a node is not responding, 

and the evicted node is re-started to make it a part of cluster.

Causes for RAC node eviction:

Node eviction on Oracle RAC environment can be due to any of the below reasons. 

- A failure of any of the major hardware components (CPU, RAM, network interconnect).

- A server that is experiencing RAM swapping.

- When communications to the voting disk is interrupted, causing the disconnected node to be evicted and re-boot.

- Database or ASM hang condition.

Below is the list of important log files to review in case of a node eviction

- Clusterware alert log

- Database alert log

- CSSD agent logs

- CSSD monitor logs

- System Message logs (/var/log/messages)

What is Flashback feature in Oracle Database?

Oracle Flashback Database and restore points are related data protection features that enable you to rewind data back in time to correct any problems caused by logical data corruption or user errors within a designated time window.

Points to Remember

- Flashback Database command can be run either from SQLPLUS or using RMAN Utility.

- FLASHBACK DATABASE command can be used to rewind the database to a target time, SCN or a log sequence number.

- Flashback command works by undoing the changes made to the data files that exist when you run the command.

- Flashback can fix only logical failures, not physical failures.

- If the database control file is restored from backup or re-created, then all existing flashback log information is discarded.

- Avoid using FLASHBACK DATABASE with a target time or SCN that coincides with a NOLOGGING operation, it can cause block corruption.