Oracle Clusterware includes two important components that manage configuration and node membership: Oracle Cluster Registry (OCR), which also includes the local component Oracle Local Registry (OLR), and voting files.
OCR manages Oracle Clusterware and Oracle RAC database configuration information
OLR resides on every node in the cluster and manages Oracle Clusterware configuration information for each particular node
Voting files manage information about node membership. Each voting file must be accessible by all nodes in the cluster for nodes to be members of the cluster
You can store OCR and voting files on Oracle Automatic Storage Management (Oracle ASM), or a shared file system.
Oracle Clusterware 12c does not support the use of raw or block devices. To upgrade to Oracle Clusterware 12c from a previous Oracle Clusterware release on which you were using raw or block devices, you must migrate OCR and voting files to Oracle ASM or a shared file system before you upgrade.
Oracle recommends that you configure multiple voting files during Oracle Clusterware installation to improve availability. If you choose to put the voting files into an Oracle ASM disk group, then Oracle ASM ensures the configuration of multiple voting files if you use a normal or high redundancy disk group. If you choose to store the voting files on a shared file system, then select the option to configure multiple voting files, in which case you will have to specify three different file systems based on different disks.
If necessary, you can dynamically add or replace voting files after you complete the Oracle Clusterware installation process without stopping the cluster.
This chapter includes the following topics: