Common Interview Questions: Defining High availability and Disaster Recovery

Hey gang Jose back, once again to discuss some interview questions from the technology field. This can be related to Physical Hardware (Dell, HPe, Cisco etc.) or Virtual Software (VMware, EMC storage – so on and so on).. Some thoughts below:

High availability (HA) and disaster recovery (DR) are often thought of as synonymous with each other. A highly available infrastructure component or IT system is described as “fault tolerant” or having the ability to “fail over”. An example of high availability at the component level is adding redundant power supplies. At the datacenter level adding dual UPS (A/B power) adds high(er) availability to power systems. To some, this implies the system is resilient enough to survive a disaster. Implementing high availability on its own, however, does not achieve disaster recovery. So what is the difference between High Availability and Disaster Recovery?

High Availability: When a given host or virtual machine fails, it is restarted on another VM within the cluster.

Disaster Recovery: Complete plan to recover critical business systems and normal operations 

What do you guys think – and how does this fit into your planning for unexpected events?