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Hot site or cold site: How to choose the best disaster recovery strategy

Choosing the type of protection you need in the event of a disaster depends on how long your business can sustain being down. In this tip, Deni Connor discusses hot and cold sites for disaster recovery to help you determine which strategy is best for your business.

Choosing the type of protection you need in the event of a disaster depends on how long your business can sustain...

being down. And, getting applications back in operation quickly can be an arduous process, especially if you don't have a disaster recovery (DR) process in place.

Consider Peter Haas, director of technology for the Supreme Court of Louisiana, in New Orleans. Two years ago, after his offices were clobbered by Hurricane Katrina, Haas spent innumerable hours devising a DR plan.

During the aftermath of Katrina, Haas made several trips into the crime- and chaos-ridden city to retrieve servers, tapes and storage gear and install them in a DR site several hours away from New Orleans.

"The biggest entity an organization needs to think about is: 'How long can I afford to be down?'" says Haas. "We asked ourselves that question, and after Katrina we realized we can't afford to be down much at all."

Haas installed CA's WANSyncHA to replicate his Exchange, Oracle and SQL servers in real time to a location in Baton Rouge. "If we had a disaster right now, we could be back up in under an hour," says Haas.

The hot site Haas implemented is fully equipped with all the server, network, storage gear and applications to continue operations pretty much unabated. This is also the most expensive of the DR options.

Instead of hot sites, some companies rely on cold sites, which are less expensive. However, customers need to obtain, provision, install and configure all the equipment in the event of a disaster. In between the hot site and cold site, both in availability and cost, is the warm site, where computers and network gear may be installed but not configured, upgraded or in operational readiness.

"It really comes down to the urgency a company needs to recover their environment," says Jim Grogan, vice president of consulting product development for SunGard Availability Services. "If the recovery time objective (RTO) is measured in days, it is going to mean a customer needs to look at a hot site. If the RTO is measured in weeks, they might be in a position to look at the warm site and only if the RTO goes beyond that, is the cold site appealing."

Grogan says that many organizations look at cold sites not so much as a place where they would recover, but as a place for ongoing operations in the event of a catastrophe that would require them to be out of their offices for several years.

Not unlike Haas is Brian Cutler, executive vice president and CTO for Arrow Financial Services. Cutler also chose a hot site that he manages himself rather than having a collocation service do it for him. Cutler's DR site is outfitted with EMC Corp. Symmetrix gear from which he replicates data from one site to another site located 200 miles away.

Not having a DR site and with systems down, would cost Arrow Financial Services approximately $2 million a day. "The biggest factor (in choosing a hot, warm or cold site) is going to be the business decision -- how much does it cost me to be down for a day, two days, three days, etc. -- that's the key evaluation," says Cutler. "You have spent a whole bunch of money and if it doesn't cost you that much for downtime, you are wasting your money to be hot."

Haas' hot site isn't the total answer to his DR plan. Upon his recommendation, IT personnel, who work with Haas, wear USB thumb drives around their necks. Stored on the thumb drive is the company's DR plan, phone numbers of key personnel that play a part in the recovery process and other information and data files necessary for implementing the plan. Testing the plan is also crucial to the business.

About this author: Deni Connor is principal analyst for Storage Strategies NOW, an IT research firm in Austin, Texas. You can reach her at

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