Whatb is Disaster Recovery (DR)?

• Describes steps which are done to re-establish availability of the solution after an outage
• It refers to restoring systems and data to a previous acceptable state in the event of partial or complete failure due to natural or technical causes

RPO and RTO

Recovery point objective (RPO)

• Describes the interval of time that might pass during a disruption before the quantity of data lost during that period exceeds the Business Continuity Plan’s maximum allowable threshold
• RPO is the maximum duration of data loss that’s acceptable during a disaster
• RPO is used to determine the maximum amount of time between the Last available backup and potential failure point. RPO helps in determining the amount of data that the business can manage to Lose in the event of a failure
• The amount of data which can be lost while bringing the system back online after a critical failure, i.e. the point in time to which the data can be recovered
• RPO is about data loss tolerance

Recovery time objective (RTO)

• The duration of time and a service level within which a business process must be restored after a disaster in order to avoid unacceptable consequences associated with a break in continuity
• RTO is the maximum acceptable time an application is unavailable after an incident
• RTO is used to determine the maximum time a data recovery process will take. It is defined by the amount of time the business can afford for the site or service to be unavailable
• The amount of time that it takes to get the system back online after a critical failure, i.e. how long you can sustain a service interruption before you absolutely need to be back online
• RTO is about restoration goals

RLO

Recovery Level Objective (RLO) defines the granularity with which data has to be rocovered. Whether recovery is required for the whole instance, database or set of databases or specific tables. It is difficult to suddenly restore a heavily damaged system to 100%. When disaster occurs, restoring production like environment might not be possible. Therefore, RLO will be set depending on requirements and recovery scope.

RLO for Solution The solution architecture will use “Auto-failover group” for Azure SQL Managed Instance and manual failover for Azure Storage Account. “Auto-failover group” and failover feature ensure availability during region failure.