RDBMS and listener log (xml) from SQL*Plus with V$DIAG_ALERT_EXt view [ADR - Automatic Diagnostic Repository]

With the V$DIAG_ALERT_EXT (Query alertlog of the database) it is possible to read the logs of all the databases and listeners from the ADR location Great for monitoring. Now only one connection to a database is needed to see all the database alert files and listener logs registered inside the ADR structure.Yes Multiple databases.

11gR2 Clusterware :Oracle Local Registry (OLR)

In 11gR2, Oracle has introduced a new registry to maintain the clusterware resources (css, crs,evm,gip and more) in a new registry called Oracle Local Registry (OLR).
Multiple processes on each node have simultaneous read and write access to the OLR particular to the node on which they reside, regardless of whether Oracle Clusterware is running or fully functional.
By default, OLR is located at Grid_home/cdata/host_name.olr on each node.The OCR still exists, but maintains only the cluster resources.

Until Oracle Database 11gR1, the RAC configurations consisted of just one registry when running Oracle Clusterware. Shortly called OCR, Oracle Cluster Registry, maintained the cluster level resource information, privileges etc. To be precise, the OCR maintained information about 2 sets of node level resources, namely, the Oracle Clusterware Components (CRS, CSS, evm) as well as Cluster resources (DB, Listener etc).