[Morendil]

See this: http://www.slideshare.net/danmil30/how-to-run-a-5-whys-with-...

Guilt is a moral concept; when it comes to a run-of-the-mill operations mistake like yours, it does not belong in analysis of its consequences to the business. You are not a robot. You have made and will make mistakes this bad and worse.

Only consequentialist thinking should be the order of the day here; "what do we know that can prevent a similar mistake from hurting our bottom line". In this case backups are the standard, reasonable, well-known practice. Nothing will be improved by a firing or a resignation, by blaming or by shaming.

Insofar as the real root cause of the problem was not addressed, it's a reasonable prediction that any such company eventually joins the deadpool due to similar oversights.