Disaster Recovery (DR) is about maintaining business continuation in the event of system failure. It's about preparing the organization for any possible system failure and the ability to recover from it. DR planning includes multiple dimensions, which include hardware or software failure. While planning for disaster recovery, always ensure you consider other operational failures, which include a power outage, network outage, heating and cooling system failure, physical security breach, and different incidents such as fire, flood, or human error.
Organizations invest effort and money in disaster recovery planning as per system criticality and impact. A revenue-generating application needs to be up all of the time as it has a significant impact on company image and profitability. Such an organization invests lots of effort in creating their infrastructure and training their employees for a disaster recovery situation. Disaster recovery is like an insurance policy that you have to invest and maintain even when you are not going to utilize it. Similarly, during normal operations, the infrastructure typically is under-utilized and over-provisioned.
Applications can be placed on a spectrum of complexity. There are four DR scenarios, sorted from highest to lowest RTO/RPO as follows:
- Backup and restore
- Pilot light
- Warm standby
- Multi-site active-active
As shown in the following diagram, in DR planning, as you progress with each option, your RTO and RPO will reduce while the cost of implementation increases. You need to make the right trade-off between RTO/RPO requirements and cost as per your application reliability requirement:
Let's explore each of the aforementioned options in detail with technology choices. Now, the public cloud, such as AWS, enables you to operate each of the preceding DR strategies cost-effectively and efficiently.
Business continuity is about ensuring critical business functions continue to operate or function quickly in the event of disasters. As organizations are opting to use the cloud for disaster recovery plans, let's learn about various disaster recovery strategies between an on-premise environment and the AWS cloud.