My blog post last month on scalability generated many interesting internal and external conversations around reliability and uptime.  I am guilty of occasionally flippantly stating that Vindicia has a SLA that focuses on 99.99% uptime, but what this means in real life compared to, say, a guarantee of 99.9% uptime reveals fascinating business implications.

Here are the differences between the two uptime SLAs at a monthly level, courtesy Wikipedia:

99.9% = 43.2 minutes downtime

99.99% = 4.32 minutes downtime

The difference of nearly 39 minutes a month might not seem like a big deal.  However, if you are an online merchant that is going through a huge Christmas surge, that hypothetical downtime would create a significant business loss.  For example, if one of our clients would have experienced the additional downtime during their heaviest signup period in 2011, they would have lost over 50,000 new customers in that 39 minute span.  This is especially relevant because it is more likely that there would be a downtime during an extended peak surge.

If each customer is worth $20 that first year, that’s a million dollar mistake.  The reality is that the amount is greater because you have to account for the the lifetime value of those customers.  Also, don’t forget the opportunity cost:  all the customers you never sign in the first place because of the bad publicity.

Reliable infrastructure matters:  putting uptime numbers in the context of what clients do in the Digital Economy is incredibly revealing.