The RPO and RTO

RPO and RTO are part of the disaster recovery policy. It’s very important to understand the difference between RPO (Relative Point Objective) and RTO (Recovery Time Objective). The RPO is the maximum time we allow ourselves to lose. This time can be expressed in minutes, hours or, in the worst case, days. This is the time between the incident and the last backup. In the case of a very short RPO, several daily backups will be necessary.

The RTO is the time required to restore data following an incident. It is interesting to note that RPO and RTO can differ. This depends on the criticality of the data. Production data will require a shorter RPO and RTO than non-production data (general communications, etc.). An RPO and an RTO with a short duration (15 minutes, for example) will require hardware with very fast read/write response times. It is very important to classify data according to its criticality. Critical data will have a low RPO and RTO, while non-critical data will have a lower value.

Calculate the RPO and RTO

Calculate the RPO and the RTO is an important point before implementing a backup infrastructure. Different point must be considered :

RPO and Business Continuity Plans are aligned : An IT infrastructure contain different ressources. Some are highly critical, others less so. Once data has been classified according to these criteria, it is important to apply a different level to it.A resource with a high criticality will therefore have a low RPO, whereas less critical data will be assigned a higher RPO value. Applying the same RPO to all data makes no sense, apart from requiring a high budget. On the contrary, an RPO with a high value will not provide the best protection for critical data. You can found below an example of RPO :

• 15 minutes to one hour : This RPO can be used for the business critical workload of your company.

• one hour to 4 hours : The critical workload can have this RPO assigned

• 4 hours to 12 hours : Used for the data updated once a day

• 12 hours to 24 hours : Used for the date with non critical classification