They say you can’t be ‘up’ all the time, but when it comes to business-critical websites, you kind of have to be up… all the time. There is no foolproof way to avoid downtime completely, but knowing that it’s expensive - both in upfront costs (immediate costs of resource allocation and customer frustration) and in the longer term (revenue and loss of customers and their trust) - is ample incentive to avoid it at all costs.