Why build a High Availability Network?

What is a High Availability Network?

Network which provides a non-single point of failure.

Single Point of Failure

Let’s first review how a network with a single point of failure looks like.

An example of that network is a single server.

A configuration where a web application is hosted on a single server is an example of a network with a single point of failure. In this case if the server restarts or fails, your website/application will be not available. In some situations it will be a short outage of just a couple of minutes for the server to restart and update, in another case the outage can be longer while the server recovers.

The single server model can be extended to separate an application server and database server into two servers. This will provide better performance for an application, but it will still be a single point of failure.

1. Application server – restart will bring application down
2. DB server – restart will bring application down

High Availability

Now that we know what a single point of failure looks like let’s review the High Availability model

High Availability is created by a minimum of two of the same types of equipment.

What does this mean?

1. Two Load Balanceres for incoming traffic
2. Two Application server
3. Two Database Server in Active-Active mode for data replication

With this setup, any server failure/restart will keep the application up and running.

The user request is coming through LB (LB is set with two LB that it is in High Availability mode – all cloud provides provide this service in HA mode)

LB is configured with two back-end application servers to send user requests to an active back-end server.

Each application server is connected to a single database server.

Database servers are set with replication Active-Active, so that any change that happens on one DB is replicated to the second database and the change is available for application on the second server.

An improved version of this solution will be to add a Load Balancer for the database service.
Using an LB you can send traffic to any active database server or send it to one server which will work as a primary server and in the case of a failure the server traffic will switch to the secondary server.

What network structure would you like to see your application running? Single point of failure or High Availability?

Running your application using Oracle Cloud Infrastructure with the latest cloud technology.

Send me a message to discuss the options.

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