Most of the times both these terms are used interchangeably however we should have a clear distinction of these in mind. Particularly while dealing with the disaster recovery (DR) and high availability (HA) scenarios.
One word difference
Major difference lies in one word i.e. data. HA does not involve data recovery aspects while DR do as name indicates.
High availability (HA)
- It is the system’s ability to remain accessible in the event of a system component failure
- It involves multiple levels of fault tolerance and/or load balancing capabilities into a system
- It does not include the redundancy or data recovery abilities
- Service downtime does not exist or is in seconds
Disaster Recovery (DR)
- It is the process by which a system is restored to a previous acceptable state, after a natural or man-made disaster
- DR involves recovery of data and services within some down time
- Downtime depends upon the option used along with the HA involved
- For DR, measurable characteristics, such as Recovery Time Objective (RTO) and Recovery Point Objective (RPO) drive our DR plan