When it comes to implementing your business continuity plan what strategy do you adopt for the disaster recovery element? (for a description on the difference between Disaster Recovery and Business Continuity please see my article on Disaster Recovery or Business Continuity?).
You may have heard the terms hot, cold and warm recovery, but what do they mean, and what are the advantages and disadvantages of each service?
Hot standby is normally available to the users within minutes of a disaster situation. This level of service is achieved by total duplication of the computer systems covered (hardware, software and data). There will also be a requirement for a resilient network connection into the Hot Site.
Benefits – Available immediately; dedicated to (customer).
Disadvantages – Cost; Complexity, management.
Warm standby is normally available to the users within hours of a disaster situation. This is by far the most common type of service utilised by for I.T. disaster recovery, and typical recovery times range from 8 hours to 24 hours (dependent on complexity, location and data volumes).
The service can be delivered from a remote recovery centre, or alternatively, delivered to site in the event of a disaster. Depending on the equipment involved the configuration may be installed within an existing facility or a mobile recovery unit.
It should be noted that whilst the Hot standby option is normally dedicated to one customer, Warm standby is delivered on a subscription basis. Industry standards are between ten and twenty five subscribers per configuration. Availability is therefore not guaranteed in the event of a disaster. Testing is also normally to a predefined number of days P.A.
Benefits – Lower cost; reasonable availability.
Disadvantages – Availability; recovery timescales are longer; limited testing available; only available for a limited period following a disaster.
Cold standby is the provision of computer and people facilities that are made available to the client within a few hours of the incident. Unless the service is backed up by a contract to supply the necessary computer equipment, the recovery period is likely to be several days. It is not unusual for Warm and Cold standby services to be combined, giving a very flexible approach to recovery.
Fully serviced office space is also available on a subscription basis. These are usually equipped with PCs, servers, printing facility and a network infrastructure. These would be described as Business Recovery Centres, and could also incorporate Cold space for central systems.
Benefits – Lower cost; large amount of available space (can accommodate large systems). Business recovery Centres can accommodate several hundred people.
Disadvantages – Availability; recovery timescales are longer; limited testing available; only available for a limited period following a disaster; additional recovery services needed.