Database Reference
In-Depth Information
High Availability Without Tears
ODAs provide high availability through easy-to-install RAC and RAC One deployments. In addition to provisioning
high availability on a single appliance, ODAs make it easy to deploy Data Guard to extend the high availability solution.
These deployments can cross data centers to provide geographic protection. Oracle assists the Data Guard deployment
process through OEM, one-button ODA Data Guard deployment scripts, and supplemental documentation focused on
deploying Data Guard on ODAs. In addition to streamlined Data Guard deployments, ODAs support high availability
through higher levels of stability because it is a packaged solution tested as a single unit.
The grid and database portions of ODA patches can be deployed in a rolling fashion. At the time of writing,
the infrastructure portion of ODA patches requires the clusterware to be completely down on both nodes, but this
may change in the future. RAC One provides high availability capabilities for both production and nonproduction
instances that are designed to run on only one of the two ODA nodes, but can be failed over to the second ODA node.
ODAs jump-start high availability implementations by greatly reducing the expertise levels required to deploy a
RAC solution. This includes eliminating the need to perform a RAC interconnect design, researching all of the RAC
requirements and best practices, provisioning ASM, eliminating all single points of failure, and all other aspects of a
well-architected RAC cluster.
High availability is also achieved from the deployment of standard, tested configurations and the choice of either
double or triple mirroring all ASM disk extents. The loss of a disk doesn't take the system down. The ODA operating
system also implements the Oracle Linux unbreakable kernel (UEK). ODAs are supported by a dedicated Oracle
engineered system support team that has an in-depth knowledge of the platform.
The majority of the hardware components are redundant. An ODA has two server nodes and redundant power
supplies. The system interconnects between the system components are redundant and are implemented by SAS
cables in the current X3-2 model.
Disk replacements are easy to perform on an ODA. Simply flip a switch on the front of the storage unit, pull the
drive out, slide the new drive in, and flip the switch back.
ODAs reduce the number of moving parts needed to implement high availability. Fewer moving parts and fewer
handoffs result in higher availability in most cases.
There are a number of high availability deployment patterns:
•
Active-Active
. This pattern is implemented as RAC deployed on an ODA, providing the ability
to load balance processing across two nodes and failover between the two servers.
•
Active-Passive
. This pattern is implemented through RAC One, RAC, and/or Data Guard.
Processing is configured to run on a single node. Failover is supported by RAC One or RAC
within an ODA. Failover across ODAs, including the ability to failover across geographic
distances, is handled by Data Guard.
Achieving high availability requires additional designs, such as RAC services, and role-based services if Data
Guard is part of the solution. The effectiveness of your high availability implementation will be directly proportional
to the amount of design and testing that go into the solution.
Costs and Value Proposition
ODAs do not fit the traditional build vs. buy purchasing model. A company can certainly choose to build their own
commodity hardware-based infrastructure. However, the typical company doesn't have the resources to build its
own engineered system. Regardless, check out the Oracle “build vs. buy” ODA videos. You'll find some videos on the
main Oracle ODA product page and Oracle's YouTube channel detailing the ease of deployment and the reasons why
you want to give serious consideration to the value proposition of buying a better, prepackaged solution. Some of the
videos have an element of humor, so they are very viewable. The content is dynamic, so we're not including any web
links because they are subject to change. However, finding them is easy enough.
