RES04-01 Defining the RPO and RTO for an Application System

Before designing DR, determine the DR objectives of an application system based on the importance of the application system. Typically, the DR objectives are defined by the RPO and RTO metrics.

• RPO: indicates the allowed volume of data loss, which is related to the data replication period or continuous replication delay.
• RTO: indicates how long services can be interrupted during recovery. It depends on how the services are deployed and switched over at the disaster recovery site.
• Risk level

  High

• Key strategies

  Service importance varies depending on the service systems. Define the importance of various services in an application system and the RPO/RTO requirements. Core services require minimal downtime to ensure quick service recovery and keep service continuity, so use active-active or multi-active DR for core services. Important services allow a certain duration of service interruptions, so use active/standby DR for important services. General services tolerate service interruptions in days, so use remote backups for general services. Interruptions of unimportant services do not have impact on customers, so they do not require DR.