Here's a question I've been getting a lot recently: "how far apart should I locate my primary data center from my farthest recovery data center?" Unfortunately, the answer is "it depends". There is no hard and fast rule for how far apart your sites should be, but here is my basic rule of thumb: the sites should be far enough apart that they are not subject to the majority of the same risks. Whether it's winter storms, power outages, or terror threats, you need to make sure that it's highly unlikely that a single event could take down both sites.
But seriously, just give me a number. Ok, ok, I have some numbers. In the chart below you can see how far apart companies were locating their recovery sites in 2007 and in 2010. What's interesting here is that between 2007 and 2010, survey respondents reported shorter distances between primary and secondary data centers. In 2007, 22% of respondents reported that the distance between their primary data center and farthest backup data center was greater than 1,000 miles, while in 2010, only 12% claimed this distance.
You want 2013 data? We are currently collecting that data now in our Forrester/Disaster Recovery Journal Survey which I highly encourage you to take here.
So, does that mean farther apart is better? Not necessarily! Consider the following:
Distance ≠ safety. Just because sites are far apart, doesn't mean they can't experience the same risks. For example, a company that has their primary site in South Florida and a recovery site in North Carolina would have significant distance between the sites, but could still both be impacted by a single hurricane.