Disaster Recovery (DR) strategy

Comparison of DR solutions √ Cold, Warm, Hot and Active-Active

Disaster Recovery or DR is the technical part of the BCP which determines how IT systems and data are updated following a major incident or disaster. DR strategy to be chosen according to defined RTO and RFMOS objectives.

1. Backup & Restore
   System restoration from backup copies.
   RTO: hours/days
   RFMOS: 0 - 24h+
   The cheapest option, but with a longer downtime and higher risk of data loss.
2. Cold Site
   Replacement environment without pre-installed systems. During the incident, the infrastructure must be installed and restored.
   RTO: 24:48h+
   Lower costs, but slow renewal.
3. Warm Site
   Partially prepared backup environment with configured systems and periodic data synchronization.
   RTO: hours
   Balanced solution between costs and recovery speed.
4. Hot Site
   Fully generated backup environment with near real-time data replication.
   RTO: minutes
   RFMOS: close to 0
   Fast but more expensive solution.
5. Active-Active
   Two or more active environments serve traffic simultaneously. In the event of a failure of one environment, the service shall continue to operate in another.
   RTO: close to 0
   RFMOS: close to 0
   Higher availability, but more complex implementation and maintenance.

Cloud DR solutions such as AWS or Azure allow flexibility to implement these strategies also for smaller organisations.

Essential: The DR plan should be tested regularly, as an untested plan is only a document and not a reliable recovery mechanism.