One of the most important aspects of disaster recovery is to have a location from which the recovery can take
place. This location is known as a backup site. In the event of a disaster, a backup site is where your data
centre will be recreated, and where you will operate from, for the length of the disaster.

There are three different types of backup sites:

• Cold backup sites
• Warm backup sites
• Hot backup sites

A cold backup site is little more than an appropriately configured space in a building. Everything required to
restore service to your users must be procured and delivered to the site before the process of recovery can
begin. The delay going from a cold backup site to full operation can be substantial.

Cold backup sites are the least expensive sites.

A warm backup site is already stocked with hardware representing a reasonable facsimile of that found in your
data centre. To restore service, the last backups from your off-site storage facility must be delivered, and
bare metal restoration completed, before the real work of recovery can begin.

Hot backup sites have a virtual mirror image of your current data centre, with all systems configured and
waiting only for the last backups of your user data from your off-site storage facility. As you can imagine, a
hot backup site can often be brought up to full production in no more than a few hours.

A hot backup site is the most expensive approach to disaster recovery.

Backup sites can come from three different sources:

• Companies specialising in providing disaster recovery services
• Other locations owned and operated by your organisation
• A mutual agreement with another organisation to share data centre facilities in the event of a disaster

Each approach has its good and bad points. For example, contracting with a disaster recovery firm often gives you access to professionals skilled in guiding organisations through the process of creating, testing, and implementing a disaster recovery plan.

Using space in another facility owned and operated by your organisation can be essentially a zero-cost option, but stocking the backup site and maintaining its readiness is still an expensive proposition.

Crafting an agreement to share data centres with another organisation can be inexpensive, but long-term operations under such conditions are usually not possible, as the host's data centre must still maintain their normal production, making the situation strained at best.

In the end, the selection of a backup site is a compromise between cost and your organisation's need for the continuation of production.

Hardware and Software Availability
Your disaster recovery plan must include methods of procuring the necessary hardware and software for operations at the backup site. A professionally-managed backup site may already have everything you need (or you may need to arrange the procurement and delivery of specialised materials the site does not have available); on the other  hand, a cold backup site means that a reliable source for every single item must be identified. Often organisations work with manufacturers to craft agreements for the speedy delivery of hardware and/or software in the event of a disaster.

Availability of Backups
When a disaster is declared, it is necessary to notify your off-site storage facility for two reasons:

• To have the last backups brought to the backup site
• To arrange regular backup pickup and dropoff to the backup site (in support of normal backups at the backup site)

Connectivity to the Backup Site
Depending on the disaster recovery plan and the nature of the disaster itself, your user community might be located miles away from the backup site. In these cases, good connectivity is vital to restoring production. This includes not only data but also voice traffic.

Moving Back to Normality
The disaster recovery plan must address returning to normal. The new data centre must be outfitted with all the necessary hardware and software; while this phase often does not have the time-critical nature of the preparations made when the disaster was initially declared, backup sites cost money every day they are in use, so economic concerns dictate that the switchover take place as quickly as possible.