Quote Originally Posted by tamilselvan
Yes, you are partially right. In general, after a checkpoint, the redo in the redo log files is no longer needed for crash/instance recovery. However, the redo logs may be needed for instance recovery if ta single transaction's redo size is greater than the redo log file size.
For example, You update millions of rows in table and then before commit/rollback, the system crashed even though several log switches occurred during the update process.
Another example is when you clone the database, the recovery process may ask you to enter redo log files which are older than the current redo log.
If the redo size of a single transaction is greater than the size of one or few redo logs but not the total redo logs group size then I believe Active not just Current redo logs will be needed for transaction recovery during instance recovery.

If in case the redo size of a single transaction is greater than the total size of all the redo logs groups then most probable you will bump the "Checkpoint not complete" error. So, I don't think there's going to be a several log switches that could occur.