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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