What is oracle clusterware? What is the advantage of oracle clusterware?
Oracle Clusterware is a software that provides clustering features to RAC databases on a set of servers. It enables the cluster nodes, Oracle RAC instances, to communicate with each other and act as a one database server serving the database users.
RAC has two components named Oracle Grid Infrastructure and Oracle RAC. And oracle grid infrastructure combines oracle clusterware and oracle ASM. Oracle clusterware also has two components, oracle clusterware registry(OCR) and voting disk.
Oracle clusterware is installed separately on a nonshared oracle home and has dedicated Operating system user named “grid”. The grid user is the owner of the oracle grid infrastructure and oracle ASM instance.
Oracle clusterware is software required to run oracle RAC option of oracle database software. It consists of several process components which provide event monitoring, high availability feature, process monitoring and group membership of the cluster.
Besides, it also tracks the configuration and status of resources such as database services, ASM instances, RAC databases, database services, listeners, ASM disk groups and VIP addresses. Furthermore, the status and configuration information of these resources are stored in OCR (Oracle Clusterware Registry) shared storage.