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Redundant Site

A redundant site is an exact production duplicate of a system that has the capability to seamlessly operate all necessary IT operations without loss of services to the end user of the system. A redundant site receives data backups in real time so that in the event of a disaster, the users of the system have no loss of data. It is a building configured exactly like the primary site and is the most expensive recovery option because it effectively more than doubles the cost of IT operations. To be fully redundant, a site must have real-time data backups to the redundant system and the end user should not notice any difference in IT services or operations in the event of a disruptive event.

Note

Within the US DoD, IT systems’ criticality is measured against just one thing; how important is this IT system for fighting a war? Based on the answer, it can be issued a Mission Assurance Category level (MAC level) I, II, or III. MAC I systems within the DoD must maintain completely redundant systems that are not colocated with the production system. By definition, there is no circumstance when a user of a MAC I system would find the system non-functional. This drives up the cost of operations not only because of the extra manpower and technology a redundant site will require, but also because of the protected communications line between each backup and production system. Ensuring that the data is mirrored successfully, so that there is no loss of service to the end user no matter what catastrophic event may occur, can be a daunting task to say the least.

Hot Site

A hot site is a location that an organization may relocate to following a major disruption or disaster. It is a datacenter with a raised floor, power, utilities, computer peripherals, and fully configured computers. The hot site will have all necessary hardware and critical application data mirrored in real time. A hot site will have the capability to allow the organization to resume critical operations within a very short period of time—sometimes in less than an hour.

It is important to note the difference between a hot site and a redundant site. Hot sites can quickly recover critical IT functionality; it may even be measured in minutes instead of hours. However, a redundant site will appear as operating normally to the end user no matter what the state of operations is for the IT program. A hot site has all the same physical, technical, and administrative controls implemented in the production site.

Warm Site

A warm site has some aspects of a hot site; for example, readily accessible hardware and connectivity, but it will have to rely upon backup data in order to reconstitute a system after a disruption. It is a datacenter with a raised floor, power, utilities, computer peripherals, and fully configured computers.

Because of the extensive costs involved to maintain a hot or redundant site, many organizations will elect to use a warm site recovery solution. These organizations will have to be able to withstand an MTD of at least 1–3 days in order to consider a warm site solution. The longer the MTD is, the less expensive the recovery solution will be. Usually, with well-trained personnel and vendor contracts in place, a warm site can reconstitute critical IT functionality within a 24–48-hour time period.

Cold Site

A cold site is the least expensive recovery solution to implement. It does not include backup copies of data, nor does it contain any immediately available hardware. After a disruptive event, a cold site will take the longest amount of time of all recovery solutions to implement and restore critical IT services for the organization. Especially in a disaster area, it could take weeks to get vendor hardware shipments in place, so organizations using a cold site recovery solution will have to be able to withstand a significantly long MTD—usually measured in weeks, not days. A cold site is typically a datacenter with a raised floor, power, utilities, and physical security, but not much beyond that.