Contributed by Mahesh sharma, Oracle Enterprise Manager Ops Center team

In Oracle Enterprise Manager Ops Center 12c we introduced a new feature to make the Enterprise Controllers highly available. With EC HA if the hardware crashes, or if the Enterprise Controller services and/or the remote database stop responding, then the enterprise services are immediately restarted on the other standby Enterprise Controller without administrative intervention.

In today's post, I'll briefly describe EC HA, look at some of the prerequisites and then show some screen shots of how the Enterprise Controller is represented in the BUI. In my next post, I'll show you how to install the EC in a HA environment and some of the new commands.

What is EC HA?

Enterprise Controller High Availability (EC HA) provides an active/standby fail-over solution for two or more Ops Center Enterprise Controllers, all within an Oracle Clusterware framework. This allows EC resources to relocate to a standby if the hardware crashes, or if certain services fail. It is also possible to manually relocate the services if maintenance on the active EC is required. When the EC services are relocated to the standby, EC services are interrupted only for the period it takes for the EC services to stop on the active node and to start back up on a standby node.

What are the prerequisites?

To install EC in a HA framework an understanding of the prerequisites are required. There are many possibilities on how these prerequisites can be installed and configured - we will not discuss these in this post. However, best practices should be applied when installing and configuring, I would suggest that you get expert help if you are not familiar with them.

Lets briefly look at each of these prerequisites in turn:

Hardware : Servers are required to host the active and standby node(s). As the nodes will be in a clustered environment, they need to be the same model and configured identically. The nodes should have the same processor class, number of cores, memory, network cards, for example.

Operating System : We can use Solaris 10 9/10 or higher, Solaris 11, OEL 5.5 or higher on x86 or Sparc

Network : There are a number of requirements for network cards in clusterware, and cables should be networked identically on all the nodes. We must also consider IP allocation for public / private and Virtual IP's (VIP's).

Storage : Shared storage will be required for the cluster voting disks, Oracle Cluster Register (OCR) and the EC's libraries.

Clusterware : Oracle Clusterware version 11.2.0.3 or later is required. This can be downloaded from: http://www.oracle.com/technetwork/database/enterprise-edition/downloads/index.html

Remote Database : Oracle RDBMS 11.1.0.x or later is required. This can be downloaded from:

http://www.oracle.com/technetwork/database/enterprise-edition/downloads/index.html

For detailed information on how to install EC HA , please read :

http://docs.oracle.com/cd/E27363_01/doc.121/e25140/install_config-shared.htm#OPCSO242

For detailed instructions on installing Oracle Clusterware, please read : http://docs.oracle.com/cd/E11882_01/install.112/e17214/chklist.htm#BHACBGII

For detailed instructions on installing the remote Oracle database have a read of: http://www.oracle.com/technetwork/database/enterprise-edition/documentation/index.html

The schematic diagram below gives a visual view of how the prerequisites are connected.

When a fail-over occurs the Enterprise Controller resources and the VIP are relocated to one of the standby nodes. The standby node then becomes active and all Ops Center services are resumed.

Connecting to the Enterprise Controller from your favourite browser.

Let's presume we have installed and configured all the prerequisites, and installed Ops Center on the active and standby nodes.

We can now connect to the active node from a browser i.e. http://<active_node1>/, this will redirect us to the virtual IP address (VIP). The VIP is the IP address that moves with the Enterprise Controller resource.

Once you log on and view the assets, you will see some new symbols, these represent that the nodes are cluster members, with one being an active member and the other a standby member in this case.

If you connect to the standby node, the browser will redirect you to a splash page, indicating that you have connected to the standby node.

Hope you find this topic interesting. Next time I will post about how to install the Enterprise Controller in the HA frame work.

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