Supporting Software - Expert Consolidation in Oracle Database 12c - page 130

Oracle Clusterware HA Framework
Oracle Clusterware is Oracle's cluster manager that allows a group of physically separate servers combine into one
logical server. The physical servers are connected together by a dedicated private network and are attached to shared
storage. Oracle Clusterware consists of a set of additional operating system processes and daemons that run on each
node in the cluster that utilize the private network and shared storage to coordinate activity between the servers. Oracle
has renamed the foundation for RAC and the high availability framework from Cluster Ready Services to Clusterware
and finally to Grid Infrastructure. Throughout the section, the terms Clusterware and Grid Infrastructure are used
interchangeably. This section briefly describes Oracle Clusterware, discussing its components, their functionality, and
how to make use of it as a cluster framework. In this context, Clusterware serves the following purposes:

• Monitor each cluster node's health and take corrective action if a node is found to be

unhealthy by means of cluster membership management.

• Monitor cluster resources, such as networks, file systems, and databases.

• Automatically restart cluster resources on the surviving node if necessary.

For a high level overview, consider Figure 4-6 .

App Server 1 App Server 2

Ethernet
Switch

Symbols

Cluster Interconnect

Active node Passive node

Fiber Channel

Client Ethernet

FC Switch

Storage
Array

Figure 4-6. Schematic overview of Clusterware in an active passive configuration

Figure 4-6 shows the most common setup for Clusterware in an active/passive configuration. Please note that the
figure is greatly simplified to focus on the important aspects of the architecture. Beginning from the lower part of the
figure and moving up, you see a storage array providing LUNs to boot the servers from, as well as storage for the Oracle
installation and the database itself. Connectivity from the servers to the closest fiber channel switches is multipathed
to prevent single points of failure.
The file system employed for storing the operating system and Grid Infrastructure does not really matter, it
would be JFS, ZFS, or EXT3/4, depending on your flavor of UNIX. What matters, though, is that you should ideally
use Oracle's Automatic Storage Management (ASM) for the database binaries and the database files, and you need to