Failover and IT disaster recovery are both processes that help to ensure business continuity, reduce downtime, and improve system reliability after a disaster event strikes. While both are critical to ensure the health of your IT systems, failover and IT disaster recovery have differing objectives, processes and benefits. In this article, we provide an overview and the key differences of each, briefly review what failover testing is and how to perform it.
What is failover?
Failover is the process of moving applications and workloads to a secondary site when the primary site is unavailable due to a failure, IT service disruption, or any other reason.
The failover process and principles will differ slightly depending on if the applications are hosted on-premises or workloads in the cloud. When managing workloads there’s additional complexity and nuances of a failover based on dependencies on the cloud provider, networking and cloud expertise.
What is IT disaster recovery?
IT Disaster recovery is the complete strategy and process of bringing a business back to an operational state after an outage, cyber attack, or other IT service disruption. This includes restoring access to and the functioning of IT systems and applications.
Key differences between failover and IT disaster recovery
Failover is one component in an overall IT disaster recovery process. When comparing disaster recovery vs failover, the differences reside in the objectives, response times, and testing processes.
Scope and Objectives
The overarching goal for failover and IT disaster recovery are similar - make a business and IT systems operational. However, the objectives differ slightly. During a failover, the objective is to prevent a full system failure and to improve the system’s fault tolerance. Fault tolerance is the ability to deliver uninterrupted service despite component failure, making systems resilient. The objective of IT disaster recovery is to get a business to resume normal operations including getting IT systems fully back up and functional after an outage.
Failover response times
Failover response time is the amount of time it takes for a system to respond after a failover event has been triggered. During a failover, the response time depends on the system configuration and built-in high availability, but it typically ranges from zero to tens of seconds, or more.
IT Disaster recovery response times
However, IT disaster recovery response times are much more granular, and are tied to each tiering of applications outlined in the IT disaster recovery plan (DRP). Businesses often using three to four tiers, ranging in criticality to the business - mission critical, business critical and important business services. The response times are known as the recovery time objective (RTO) for applications and recovery point objective (RPO) for corresponding data.
For example, a mission critical application tier will have an RTO and its database an RPO of zero or near-zero. This minimizes the impact and helps the business recover very quickly with minimal or no impact on business operations. It is also very costly to operate and maintain. While business critical applications may have an RTO of 30 minutes or less to one hour.
Failover testing vs IT disaster recovery testing
IT disaster recovery testing is the process that evaluates if an organization's outlined disaster recovery plan is valid. It validates if data and applications can be recovered and continue operations after a disruption. There are multiple IT disaster recovery scenarios to test and various test types, each with varying degrees of effectiveness.
Failover testing is the process of evaluating if an IT system can move applications from the primary location to the secondary or recovery site. Typically, a failover test is one component of the larger IT disaster recovery plan or test.
Additionally, there are cloud services that can speed up the process. For example, AWS Elastic Disaster Recovery (DRS) automates the launch of a recovery instance used during a failover. AWS DRS allows you to perform frequent launching of AWS instances to test the failover and failback process without redirecting the traffic.
A failover testing strategy is typically aligned and a component of the greater IT disaster recovery testing strategy. Similar to testing disaster recovery in cloud computing, it’s more complex to test availability zone (AZ) or regional failovers compared to an on-premises failover due to dependencies on the cloud provider, networking and cloud expertise.
How Cutover helps with failover and IT disaster recovery
You shouldn’t have a failover plan without a broader IT disaster recovery plan. With Cutover’s automated runbooks, you can outline your comprehensive disaster recovery plan with detailed steps, assign individuals or teams to tasks, automate repetitive tasks and notify teams of updates. Additionally, you can easily track the failover tasks in the runbook to measure and report on response times, etc.
In sum, every IT disaster recovery plan should include failover as part of its process listing out the detailed tasks. The failover plan should be regularly tested and updated to incorporate any lessons learned for continuous improvement.