2000-11-27-11:07:34 Marshall Eubanks:
[...] In other words, planning for very high reliability makes you do the engineering which gives you the redundancy which makes it possible to withstand unexpected events without (too much) failure. To the extent SLA's reflect that, they should be useful, regardless of how sound the statistics are.
A reasonable and good observation to keep in mind from an engineering point of view, but I think the essence of the current complaint with SLAs is that they are completely decoupled from engineering; they seem to show up only with providers whose service is sufficiently poorly run that they never, ever approach delivering the claimed levels, and the SLA itself carries no weight since the penalties for failure (if they can be extracted at all) are too small to benefit the customer, or to influence the provider. In today's internet world they're just marketing drivel. Naturally such strong statements beg for counterexample; please, someone, tell us about providers that offer SLAs with big enough payoffs to provide some sort of incentive, who deliver on the service levels they boast about. Please! -Bennett