The two industry standard measurements of DR solutions are:

• Recovery Point Objective (RPO): This is the point in time to which systems must be recovered after an outage. This measurement defines the amount of data loss an organization can endure. Different services may have varying RPO requirements. Sometimes you may also need multiple RPOs to restore not only the latest data (that means the closest point from a time point of view), but also the oldest; in this case, we are talking about the type of retention that is required.
• Recovery Time Objective (RTO): This refers to how long it takes to recover services after the disaster. This measurement defines the amount of downtime an organization can endure. Recovery time includes fault detection, recovering data, and bringing applications back online.

Different solutions, like backup and replicas, can reach different types of RPO and RTO, as described in the following figure:

Another aspect of BC is availability, where different types of availability can be required and provided:

• HA: The system or application is available during specified operating hours with no unplanned outages. This is the most common way to manage availability at the infrastructure level and is usually measured in the availability level.
• Continuous operations: This means that a system is committed to constant availability, with no unscheduled downtime. To achieve this level, you must implement HA and continuous operations techniques that make the system more reliable and eliminate dependence on scheduled maintenance work that would require system downtime.
• Continuous availability: This is similar to the continuous operations, but the system is committed to being available always, with no scheduled or unscheduled downtime.

For the HA level, usually, a number of nines define the percentage of uptime in a given year. The following table shows the downtime that will be allowed for a particular percentage of availability:

Finally, the Service Level Agreement (SLA) is defined as an official commitment that prevails between a service provider and a service consumer. Usually, the most common component of SLA is that the services should be provided to the customer as agreed upon in the contract.