The following are the commonly followed strategies in the increasing order of Recovery Time Objective (Time taken to restore once disaster strikes) and cost.
- Backup and Restore – Complete offline. High recovery time and data loss. Less expensive.
- Pilot light strategy – Bare minimum mechanism in place to get the system back as early as possible. For example, in case of database, there could be a read replica. Application / Web servers are setup post the disaster. Comparatively less recovery time and data loss. Comparatively expensive.
- Warm mode – Completely production replica in place but it doesn’t serve the traffic. Minimum down time. Less recovery time and data loss. Expensive.
- Active mode – Replica setup as above but serves traffic. No down time and data loss. Very expensive setup.