Unfortunately, there’s no clear-cut answer to this question. Some suggest locating the backup site at least two FEMA-defined regions away, but most people shy away from setting firm guidelines measured in miles.
Instead, the geography should be dictated by the risks related to your organization’s business processes, data and physical location (a business impact analysis should reveal what these risks are). Once you’re aware of the risks you face, you can weigh the benefits and drawbacks of nearby and distant DR sites.
Nearby Disaster Recovery Site
A nearby DR site is beneficial for a variety of reasons. It’s within driving distance, making it easily accessible. If your DR site is nearby and is unaffected by an incident affecting your primary location, you can continue business operations more quickly than if your DR site were hundreds of miles away. In addition, the bandwidth costs are less, and you’re not as likely to experience significant system recovery delays due to latency issues.
However, the benefit of having a DR site within driving distance depends on the locale's risks. If your region is prone to hurricanes, earthquakes or floods, having a DR site in the same region can be risky. For instance, Hurricane Sandy was 1,100 miles in diameter — that’s more than a third of the continental United States. In regional disasters like this, your DR site could be affected by the same event as your primary facility, rendering it useless.
On the other hand, Spokane, WA is a geologically stable area whose biggest threats are wildfire and train derailment. Many businesses in these areas are comfortable with a nearby DR site as long as the site is on a different power grid.
Distant Disaster Recovery Site
Distant DR sites are beneficial because there’s less shared geographic risk. For example, if a business affected by Hurricane Sandy had had a DR site in Washington, the recovery environment would not have been compromised.
One of the significant challenges of a distant DR site is latency. When recovering data or systems across a significant distance, slower recovery times and bandwidth costs can negatively impact business continuity goals. The distance can be challenging for employees who need to be on-site as well. After a significant disaster, employees are often busy tending to their personal situations and aren’t able to travel far.
When answering the question of how far away a DR site should be from the primary site, then, it’s a matter of mitigating shared risks, not measuring miles. For more about the role of location in data vaulting, check out our post "Where in the World Is Your Data?"