By Mike Talon
Disaster recovery sites don't necessarily have to be dedicated facilities that are always on and always ready. Depending on your organization's specific needs, you can design facilities and systems to obtain the right type of recovery space without overspending. Let's look at three options for DR sites.
Cold sites are the least expensive methodology for creating a DR site. Cold sites are just space in another facility, which the company usually already owns.
Server systems and other required hardware and software don't exist within cold sites. Instead, space is available for the installation of this equipment at a later time.
With a cold site, your recovery time objective (RTO), which determines how long your organization can afford to remain offline without impacting business, must be long enough to allow you to acquire the necessary hardware and software and to configure and install all the necessary systems. While this keeps your initial costs very low, the cost of shipping hardware and software immediately to alternate locations can be quite expensive during the actual disaster.
Warm sites contain the space and the basic equipment and software required to bring the business back into production with a minimum of configuration required. In general, you don't completely install and configure systems. Instead, you ensure that alternate hardware platforms are ready to go, and you'll only need to install and configure them with the correct software packages.
The drawback of a warm site is that you must manually configure all the software and systems at the time of failover, with few exceptions. But the benefit of a warm site is that it offers a very good midpoint between budget and full availability.
With a hot site, you've installed and preconfigured data systems, but you generally keep them offline until failover is necessary.
While hot sites are the most expensive methodology for a DR site, they also require the least user intervention at the actual time of failover. You'll only need to restart systems and, if necessary, restore data to the individual system in question. In many cases, replication systems can allow you to avoid performing any form of restoration, and failover software can bring systems online without user intervention, if appropriate.
Which type of site is best for your organization depends on several factors. For example, budgetary restrictions may limit you to using only cold or warm sites.
Technology may also play a role in determining which type of DR site you use. Certain technologies may not allow you to keep a hot site as a viable option.
If both your technology and budget allow you to use a hot site, this is generally the best option when creating a DR site. However, hot sites aren't mandatory unless your organization's RTO or recovery point objective (RPO) is such that a hot site is the only way to meet those requirements.
Cold or warm sites are very viable options for smaller organizations, especially those that can borrow physical facilities from other companies or partners, and for mid- to enterprise-tier organizations with data systems that don't have high availability needs.
Choosing which type of DR site is best for your organization is simply a matter of examining the requirements for recoverability for different data systems on a case-by-case basis.
Mike Talon is an IT consultant and freelance journalist who has worked for both traditional businesses and dot-com startups.