Which disaster recovery measurements do you really need? The answer is the ones that are effective in helping you to plan and execute good DR. So your choice will naturally depend on your IT operations. The two ‘classics’ of the recovery time objective (RTO) and recovery point objective (RPO) are so fundamental that they apply to practically all situations. But suppose your organisation is running a service-oriented IT architecture with business applications like ERP using resources supplied by other servers. If some of the servers cannot be recovered satisfactorily, there may be a secondary impact elsewhere. How can you measure this situation and define a minimum acceptable level of recovery?
This is where the recovery consistency objective (RCO) can be applied. The metric it uses is Recovery Consistency Characteristics (RCC), which measures the usability of recovered data by associated applications. In other words, you’re measuring the consistency of distributed data within interlinked systems after a disaster incident. RCO and RCC can be defined for a particular enterprise process such as manufacturing to order. They give you an idea of how close the real state of business data (its ‘freshness’ for instance) is to the required state of those data for the process to function correctly.
RCO becomes increasingly important as IT installations grow in complexity and mission-critical business processes overlay multiple systems. The basic formula for calculating RCC and RCO is ((total number of entities) – (number of inconsistent entities))/(total number of entities). So if you require an RCO of 100%, that means you have zero tolerance of inconsistent entities, and vice versa. Manufacturing, logistics and financial systems (in banking, for example) typically require high or very high RCOs. Other applications such as CRM or HR applications may function sufficiently well with lower RCOs. Whatever the case, remember that an RCO is a step up in sophistication compared to RTO and RPO. This is because RCO applies to an interlinked group of systems, whereas RTO and RPO apply to individual systems.