Oracle internals, debugging and undocumented features
Oracle Grid Infrastructure 188.8.131.52 introduces new feature called Redundant Interconnect
allowing for Oracle Supplied redundancy for the cluster interconnect.Redundant Interconnect Usage
enables load-balancing and high availability across multiple (up to 4) private networks (also known as interconnects).Redundant Interconnect Usage creates a redundant interconnect when you identify more than one interface as private.
With this new feature, multicast network communication on the private interconnect network is utilized on bootstrap to establish communication with peer nodes in the cluster, once communication is established network communication is then switched to unicast.
This mulitcast communication utilizes the 184.108.40.206 address (port 42424) on the private interconnect network.Therefore multicast on the private interconnect network must be enabled and properly
functioning on all cluster nodes for the mulitcast address 220.127.116.11 (port 42424).
Should multicast communication fail, the end result will be the inability for the node to join the cluster.
Starting from 18.104.22.168 onwards an I/O write error to a datafile will now crash the instance.
Before this fix I/O errors to datafiles not in the system tablespace
offline the respective datafiles when the database is in archivelog mode.
Oracle indroduced new hidden parameter _datafile_write_errors_crash_instance to control instance crash on I/O error.
Default is true .
So if you decide to keep old setting set this parameter to false.