RAC

[satish]

Hi erman,

 I m not getting why LMS will request LGWR flush when transfering blocks between instances.Could you plz let us know the reason behind this

Dbversion 12.1.0.2
2 node RAC

Thank you.

[ErmanArslansOracleBlog]

This is done for maintaining the consistency in RAC environments.

Consider the following scenario;

What if the instances crash right after the block is transferred to the other node?

That is why, before sending a current mode block LMS process will request LGWR for a log flush.
Until LGWR completes its job and sends a signal back to LMS process, LMS will wait on 'gcs log flush' wait event.
This is done when the requested "Current Mode" block has uncommited changes.