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.
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.
- Sometimes too far is too risky. Excessive distance can be troublesome as well, especially when it comes to latency and bandwidth—replicating data between the sites can become expensive and slow. This may end up impacting recovery point objectives.
- The people factor. If the recovery procedures require any staff to physically enter the data center, distance from corporate headquarters can be a barrier to recovery. Remember that during a large scale disaster, your employees will most likely be most concerned with their families and property, and may not be willing to get in a car and drive for 8 hours to reach the recovery site.
How far apart are your primary and secondary sites? Are you comfortable with the distance or do you wish it was farther, or closer?