About Oracle Cluster Registry

About Oracle Cluster Registry
About Oracle Cluster Registry


Oracle Cluster Registry (OCR) is a file that contains information about the cluster node list and instance-to-node mapping information. OCR also contains information about Oracle Clusterware resource profiles for resources that you have customized. the voting disk data is also backed up in OCR.
OCR contains cluster node information and instance-to-node ing information. Custom cluster resources are also included, and voting disk data is also backed up to OCR.


Each node in a cluster also has a local copy of the OCR, called an Oracle Local Registry (OLR), that is created when Oracle Clusterware is installed. multiple processes on each node have simultaneous read and write access to the OLR participant to the node on which they reside, whether Oracle Clusterware is fully functional. by default, OLR is located at Grid_home/cdata/$ HOSTNAME. olr
Each node in the Cluster also includes a local OCR backup called OLR, which was created during cluster installation. read and Write local OLR. by default, OLR exists in $ Grid_home/cdata/$ HOSTNAME. olr


Managing the Oracle Clusterware Stack
Note:
Do not use Oracle Clusterware Control (CRSCTL) commands on Oracle entities (such as resources, resource types, and server pools) that have names beginning with ora unless you are directed to do so by Oracle Support. the Server Control utility (SRVCTL) is the correct utility to use on Oracle entities.
Do not use the crsctl command to start the process name starting with ora, unless notified by oracle support. to start this process, use srvctl




Starting Oracle Clusterware


You use the CRSCTL utility to manage Oracle Clusterware. if the Oracle High Availability Services daemon (OHASD) is running on all the cluster nodes, then you can start the entire Oracle Clusterware stack (all the processes and resources managed by Oracle Clusterware ), on all nodes in the cluster by executing the following command on any node:


Crsctl start cluster-all
---- If the OHASD process has been started on all nodes, you can use the preceding command to start the entire cluster.




You can start the Oracle Clusterware stack on specific nodes by using the-n option followed by a space-delimited list of node names, for example:


Crsctl start cluster-n racnode1 racnode4
---- Use the above command to start a single node in the Cluster




To use the previous command, the OHASD process must be running on the specified nodes.


To start the entire Oracle Clusterware stack on a node, including the OHASD process, run the following command on that node:


Crsctl start crs
----- Use the preceding command to start cluster resources, including the OHASD process, but only on one node.




Stopping Oracle Clusterware


To stop Oracle Clusterware on all nodes in the cluster, execute the following command on any node:


Crsctl stop cluster-all
---- Stop resources of all nodes in the Cluster


The previous command stops the resources managed by Oracle Clusterware, the Oracle ASM instance, and all the Oracle Clusterware processes (partition t for OHASD and its dependent processes ).


To stop Oracle Clusterware and Oracle ASM on select nodes, include the-n option followed by a space-delimited list of node names, for example:


Crsctl stop cluster-n racnode1 racnode3
---- Stop a Single Node


If you do not include either the-all or the-n option in the stop cluster command, then Oracle Clusterware and its managed resources are stopped only on the node where you execute the command.


To completely shut down the entire Oracle Clusterware stack, including the OHASD process, use the crsctl stop crs command. CRSCTL attempts to gracefully stop the resources managed by Oracle Clusterware during the shutdown of the Oracle Clusterware stack. if any resources that Oracle Clusterware manages are still running after executing the crsctl stop crs command, then the command fails. you must then use the-f option to unconditionally stop all resources and stop the Oracle Clusterware stack, for example:


Crsctl stop crs-all-f
---- Force disable crs
Note:
When you shut down the Oracle Clusterware stack, you also shut down the Oracle Automatic Storage Management (Oracle ASM) instances. if the Oracle Clusterware files (voting disk and OCR) are stored in an Oracle ASM disk group, then the only way to shut down the Oracle ASM instances is to shut down the Oracle Clusterware stack.