The failure of critical components of computing infrastructure cannot be predicted. However, when running a mission-critical system, high availability is expected at all times. In clear terms, high availability denotes the functioning of computing infrastructure regardless of the status of components.
It is essential to state that to ensure high availability on any computing infrastructure, certain elements have to be in place. Firstly, the availability of redundant elements as a back up for critical components. From another perspective, a monitoring system should always be in place. This collects data to detects a failure in any running system. Most importantly is a failover switch that can analyze the data collected and swiftly switch over to the redundant components.
As an enterprise Microsoft Azure user, you should aim for a high level of availability. This is due to the variety of tools and mechanisms provided to help users achieve high availability. We’ve come up with checklists that can help you achieve high availability on Microsoft Azure;
- Design a High Availability Architecture
To ensure high availability, you need to be able to predict the type of failures you are likely to encounter. Identify the implications of these failures while itemizing recovery strategies.
It’s technically referred to as a ‘Failure Mode Analysis,” and it is tasked with identifying the redundancy level of different components. In essence, the architecture should be designed to avoid a single point of failure while utilizing load balancing between redundant components.
However, put a mind to cost when designing the architecture as it’s likely to increases your costs. Most importantly, ensure that the systems are designed to fail gracefully without leading to any disruption in service.
- Regular and Scheduled End-To-End Testing
Put your system under different failure scenarios and see how they respond. You can employ fault injection testing to carry out a combination of failure while also measuring the recovery time. The recovery time is a factor of how the redundant components are designed to take on the load shed.
Your end to end testing should take into consideration failover and failback. To get a clear view of how your system performs realistically, carry out loading. While this is ongoing, observe how the failure mechanism put in place responds.
Don’t also forget to carry out planned and unplanned disaster recovery exercises. During this time, see how your team carry out the disaster recovery plan.
- Consistent Application Deployment
Having an automated application deployment will minimize the probability of errors and failures; this will create a faster recovery plan. The implementation of application code, when not planned, could result in failure.
Put in a release process that updates the system with minimal disruption of service. Aim for rolling out updates that will not lead to downtime of critical components. Plan to utilize a blue-green release to have your cloud environment available at the same time.
In all of these, institute a rollback plan that can quickly return systems to a working version. Always set the component up for restoration to the “last known good” version.
- Prioritize Monitoring of Application Health
In time detection of issues is critical to ensuring high availability on Microsoft Azure. There are Azure health probes that provide current data about service availability. In carrying out these check functions, do it from outside of the application.
It would be best if you looked out for ill health in the metrics rather than the total failure of any component. When you pay attention to degrading metrics, you can arrest possible failure in time. Put in place an early warning system that tracks key indicators of application health and inform the team in time.
More importantly, put an eye on the allowed limits of your Azure subscriptions. Whenever you overload the limits, failure is imminent.
- Employ Azure Availability Zones
There’s also the use of multiple availability zones to guarantee the high availability of Azure subscriptions. Being separate data centers, the availability zones runs on its cooling, power, and network.
Running services on multiple availability zone is encouraged as it guarantees resilience to failure, and prevent failure in the primary data centers.
To be frank about cloud computing, anything that can fail, will. It’s just a matter of time. However, what is important is what happens and how you respond to the imminent failure.
Prepare your cloud computing environment for the expected failure by making use of this high availability checklist.