Business Continuity is essentially a special case of a disaster recovery strategy. At a basic level, business continuity entails that in the event of a disaster there will be zero downtime (RTO = 0) and no data loss (RPO = 0). RTO and RPO are defined as follows:
- Recovery Point Objective (RPO) defines the acceptable amount of data loss measured in time. If a disaster occurs and recovery is necessary, what is the acceptable age of the data? In the case of business continuity the RPO is 0.
- Recovery Time Objective (RTO) defines the acceptable amount of time allowed from the identification of a disaster through the disaster recovery process for the full restoration of critical operations. If a disaster occurs and recovery is necessary, what is the acceptable amount of time to restore operation? In the case of business continuity the RTO is 0.
The strict requirements of business continuity narrows the technology options on several levels. To achieve business continuance, the disaster recovery (DR) site must be a hot-site meaning the infrastructure (servers, storage, switches) must exist to bring all data and applications online immediately. Overall the following requirements must be met:
- The WAN bandwidth to the DR site must be adequate to achieve synchronous mirroring or continuous data replication between sites. WAN acceleration can help to reduce overall costs in achieving this requirement.
- Technology that is capable of maintaining a synchronous mirror or continuous data replication stream must be utilized for all data (work product, application, server personalities, etc.). Sizable implementations will require Storage and SAN products with features of replication, synchronous mirroring, and snapshot.
- Business continuity often involves custom scripting. Many technology options automate as many of these functions as possible to simplify the task of achieving business continuity.
- Virtualization of both storage and servers will greatly simplify any business continuity implementation. By consolidating storage and servers into distinct groups or entities the DR site can be brought online simply by activating these entities. With the release of the VMWare Site Recovery Manager, most layers of the business continuance process can be automated.