Oracle Local Registry (OLR) in RAC - 11gR2
In 11gR2, addition to OCR, we have another component called OLR installed on each node in the cluster. It is a local registry for node specific purposes. The OLR is not shared by other nodes in the cluster. It is installed and configured when clusterware is installed. Why OLR is used and why was it introduced. In 10g, we cannot store OCR’s in ASM and hence to startup the clusterware, oracle uses OCR but what happens when OCR is stored is ASM in 11g. OCR should be accessible to find out the resources that need to be started or not. But, if OCR is on ASM, it can’t read until ASM (which itself is the resource of the node and this information is stored in OCR) is up. To answer this, Oracle introduced a component called OLR. Ø It is the first fi le used to startup the clusterware when OCR is stored on ASM. Ø Information about the resources that needs to be started on a node is stored in an OS file called ORACLE LOCAL REGISTRY (OLR). Ø ...