when bidirectional replication is set up.
If ReplicaModifications is enabled in the replication
configuration, sync metadata updates to source if
replication rules are met. By default, if this
configuration is unset, MinIO automatically sync's
metadata updates on replica back to the source.
This is an optimization to save IOPS. The replication
failures will be re-queued once more to re-attempt
replication. If it still does not succeed, the replication
status is set as `FAILED` and will be caught up on
scanner cycle.
Delete marker replication is implemented for V2
configuration specified in AWS spec (though AWS
allows it only in the V1 configuration).
This PR also brings in a MinIO only extension of
replicating permanent deletes, i.e. deletes specifying
version id are replicated to target cluster.
