A cold site is a type of backup site to which a business or government agency can go if the primary site is destroyed, damaged, or otherwise rendered inoperable. Cold sites are generally the least expensive type of backup site to establish, but they are also somewhat less effective than more expensive options that can be operational within hours of a primary site going offline. These types of backup sites are often used for businesses and services that utilize the Internet and internal networking extensively for daily operations. A cold site will not usually have any hardware or technology at the backup site, and so it may take days or even weeks for the site to become operational after the loss of a primary site.
The basic purpose for a backup site stems from the idea that a natural or man-made disaster can potentially cripple a business or government agency by destroying or damaging its primary operating site. In order to minimize the negative impact this sort of event would have, a backup site is established to allow people within the business or agency to move and resume operations. There are generally three types of backup sites: hot sites, cold sites, and warm sites, with a cold site being the least expensive to establish.
A cold site is a backup site that does not have hardware and equipment already in it for operational use. This means if a company with an operational staff of 20 people, each with a computer and two monitors, has to transfer to a cold site, then they will need to get all of the necessary equipment as quickly as possible to the site to resume operations. While a cold site is less expensive to establish, since it is really only a location and does not have the hardware needed, it can be very expensive to actually utilize in case of an emergency.
Hot sites are far more expensive to establish and have all of the necessary hardware and technology already at the site while the primary site is still in use. This type of backup site is basically a copy of the primary site, and software can even be used to allow data from the primary site to be transferred and saved at the hot site in real time. A warm site is something of a mixture of a hot site and a cold site, with hardware ready for immediate use, but potentially less powerful machines and data backup that may be several days or weeks old.