How much data are you willing to lose?

Posted in Hardware by Dan on December 14th, 2009

Following the unfortunate demise of Jeff Atwood and Phil Haack’s blogs, the resultant schadenfreude on Reddit, and Jeff’s subsequent discussion of StackOverflow’s back-up process, I’m going to share with you everything that I know about back-up procedures. This won’t be a long post, I’m not a sysadmin.

You might keep frequent on-site back-ups to reduce the inconvenience of routine problems such as hardware failure, but it’s the off-site back-ups that ultimately determine how resilient you are in the face of real problems (fire, flood, etc.).  In that final analysis only the off-site back-ups matter. Making more, or more frequent, on-site back-ups will not help if your off-site back-ups are non-existent, broken (a.k.a. untested), or not frequent enough. There’s really only one question you need to ask yourself when deciding how frequently you need to back-up: how much data am I willing to lose?

If you are taking fortnightly dumps off-site but three days of data loss would kill your business then your back-up plan is worse than useless.  Sitting very still with all your fingers crossed would be a more effective disaster-prevention policy.