Unfortunately it's easy to forget that what you have is not a backup until you have tested it.<p>I remember setting up a pair of NASes for a customer, units I hadn't used before. I found that the configuration restore did not work at all and the two built-in backup tools a) would only allow a full restore of any backed-up folder and b) were unconscionably fragile, respectively.<p>Luckily this was blatant in testing and as the rest of the units' functions worked nicely, I decided not to send them back, and rolled my own backup. Which is tested, and has much better alerting/monitoring.