The decision about what kind of DR site an organization needs and its location requires careful planning and a balance of costs against any risks. There are two fundamental DR site options: internal and external. An organization sets up and maintains an internal site while an external site is owned and operated by an outside provider.
Companies with large information requirements and aggressive recovery time objectives are more likely to use an internal DR site. The internal site is typically a second data center and allows a company to recover and resume operations following a disaster at the primary center.
External site options are hot, warm and cold sites:
- At a hot site, an organization has access to a fully functional data center with hardware and software, personnel and customer data. It is typically staffed around the clock and is ready for organizations to operate their IT in the event of a disaster.
- A warm site is an equipped data center but does not have customer data. It contains some or all of the equipment found in a working data center, such as hardware and software, network services and personnel. An organization can install additional equipment and introduce customer data when a disaster occurs.
- A cold site has infrastructure to support IT systems and data, but no technology until an organization activates DR plans and installs equipment. A cold site is only an option for business systems that can be down for an extended period. An organization can use a cold site to supplement hot and warm sites in the event of a disaster that lasts a long time.
Distance is a prime consideration for an organization's DR site. A closer site allows for tighter synchronization and easier staff management. But it should be on a different power grid than the organization's primary data center and far enough away that a major disaster does not impact both places. Sites too far away, though, can create replication issues, require different staff and end up costing a lot. An organization needs to make location decisions based on the importance of data, type of possible disasters and cost.
A company can also use a cloud-based recovery site. Having DR sites in the cloud reduces the need for data center space, infrastructure and resources. Cloud DR sites can be cheaper and more viable for smaller companies, but security and bandwidth are concerns.
Other types of DR sites include mobile recovery services and colocation data centers. Mobile recovery services -- for companies that want to remain in the area of the disaster -- typically involve specially outfitted trailers that are positioned at pre-arranged locations. At colocation data centers, or carrier hotels, multiple customers install network, server and data storage devices, and connect to a variety of telecommunications and network service providers.