In today's computer-driven economy, businesses must respond to the danger of data loss and costly downtime associated with hardware and software malfunctions, equipment failure, acts of terrorism, and natural disasters. As part of every business impact analysis, company management must establish specific goals for disaster recovery, including the recovery point objective (RPO). The recovery point objective is the retroactive period to which data can be restored after a disaster and still allow the company to resume normal operations. In other words, the RPO refers to the acceptable amount of potential data loss, in terms of time, that the company can tolerate. The recovery point objective determines the frequency of key business data backup and the technology involved in that process.
Although it might seem prudent to keep all data backed up to the minute, the cost of doing so may be prohibitive, particularly if a company wishes to store information off site. Each company must carefully weigh its actual needs for recovery of critical information against the costs of a proposed recovery system. For example, banks and stock exchanges cannot tolerate any loss of data, requiring an up-to-the-minute or continuous "Point of Failure RPO." A medical office does have critical patient and financial data on its computer system, but it can resume operations if the information is restored from the backup the night before, called a "Close of Business RPO." Finally, a teenager who plays games and surfs the net on his home computer may have a "Zero RPO," meaning that he does not have a serious backup need.
In addition to the recovery point objective, a business continuity plan also contains a recovery time objective (RTO), a targeted time from the time of the failure to restoration of data. For example, a company may decide that it must resume normal activity within six hours of a disaster in order to minimize financial losses. The data retrieval systems used by the company must provide a full restoration of critical data within a six-hour window. While the RPO determines backup frequency, the RTO determines the recovery technology. Diverse modalities for backup and recovery from tapes, discs, external hard drives, online storage, and alternate physical sites connected by telecommunications systems all provide differing degrees of accessibility, security, and rate of recovery.
Several key factors enter into the determination of a recovery point objective. First, company management must segregate the information that is utterly essential to basic operations to reduce the costs of data replication and storage. If a company wants to reproduce and store all data, including noncritical data, it may have to reduce the frequency of replication in order to contain costs. For continuous recovery systems, the reliability of data replicated during the course of a long-term disaster cannot be guaranteed. If the company desires regional protection, with off site storage, the costs of maintaining dark fiber, dense wave division multiplexor (DWDM) technology, or telecommunication lines will necessitate longer RPOs.
