Recovery Time Objective and Recovery Point Objective
The recovery time objective (RTO) is the targeted duration of time and a service level within which a business process must be restored after a disaster (or disruption) in order to avoid unacceptable consequences associated with a break in business continuity.
It can include the time for trying to fix the problem without a recovery, the recovery itself, testing, and the communication to the users. Decision time for users representative is not included.
The business continuity timeline usually runs parallel with an incident management timeline and may start at the same, or different, points. In accepted business continuity planning methodology, the RTO is established during
the Business Impact Analysis (BIA) by the owner of a process (usually in conjunction with the business continuity planner). The RTOs are then presented to senior management for acceptance.
The RTO attaches to the business process and not the resources required to support the process.
The RTO and the results of the BIA in its entirety provide the basis for identifying and analyzing viable strategies for inclusion in the business continuity plan. Viable strategy options would include any which would enable resumption of a business process in a time frame at or near the RTO. This would include alternate or manual workaround procedures and would not necessarily require computer systems to meet the RTOs.
The “O” in RTO stands for objective, not mandate. In reality, tactics are often selected that will not meet the RTO. In this instance, the RTO will not be met but should still remain an objective of future strategy revision.
In a good deal of the literature on this subject, RTO is spoken of as a complement of recovery point objective (RPO), with the two metrics describing the limits of acceptable or “tolerable” ITSC performance in terms of time lost (RTO) from normal business process functioning, and in terms of data lost or not backed up during that period of time (RPO) respectively.
A recovery point objective, or “RPO”, is defined by business continuity planning. It is the maximum tolerable period in which data might be lost from an IT service due to a major incident. The RPO gives systems designers a limit to work to. For instance, if the RPO is set to four hours, then in practice, off-site mirrored backups must be continuously maintained – a daily off-site backup on tape will not suffice. Care must be taken to avoid two common mistakes around the use and definition of RPO.
Firstly, BC staff use business impact analysis to determine RPO for each service – RPO is not determined by the existent backup regime. Secondly, when any level of preparation of off-site data is required, rather than at the time the backups are offsited, the period during which data is lost very often starts near the time of the beginning of the work to prepare backups which are eventually offsited.
The RTO and RPO form part of the first specification for any IT Service. The RTO and the RPO have a very significant effect on the design of computer services and for this reason must be considered in concert with all the other major system design criteria.
When assessing the abilities of system designs to meet RPO criteria, for practical reasons, the RPO capability in a proposed design is tied to the times backups are sent offsite- if for instance offsiting is on tape and only daily (still quite common), then 49 or better, 73 hours is the best RPO the proposed system can deliver, so as to cover for tape hardware problems (tape failure is still too frequent, one bad tape can write off a whole daily synchronization point). Another example- if a service is to be properly set up to restart from any point (data is capable of synchronization at all times) and offsiting is via synchronous copies to an offsite mirror data storage device, then the RPO capability of the proposed service is to all intents and purposes 0 hours- although it is normal to allow an hour for RPO in this circumstance to cover off any unforeseen difficulty.
If the RTO and RPO can be set to be more than 73 hours then daily backups to tapes (or other transportable media), that are then couriered on a daily basis to an offsite location, comfortably covers backup needs at a relatively low cost. Recovery can be enacted at a predetermined site. Very often this site will be one belonging to a specialist recovery company who can more cheaply provide serviced floor space and hardware as required in recovery because it manages the risks to its clients and carefully shares (or “syndicates”) hardware between them, according to these risks.
If the RTO is set to 4 hours and the RPO to 1 hour, then a mirror copy of production data must be continuously maintained at the recovery site and close to dedicated recovery hardware must be available at the recovery site- hardware that is always capable of being pressed into service within 30 minutes or so. These shorter RTO and RPO settings demand a fundamentally different hardware design- which is for instance, relatively much more expensive than tape backup designs.
If very high volumes of high value transactions are to be planned for, then the production hardware can be split across two sites; with a high bandwidth network connection between the two sites constant mirroring of data can be achieved. If the user community is dispersed or at least split across two geographic areas, then the configuration is resilient to single site Major Incidents- with zero RTO and RPO being achievable, and very often little loss of service being experienced at most times of day.