_95th%ile is not a robust mechanism for billing_ It neither addresses variance nor average use effectively and can be gamed quite easily. It's some kind of best fit system for billing buyers with "normal behaviour".
Where in maths class did they ever say that scraping off the highest n percent of a data set in isolation, gives a good indication of anything? Don't you need to look at the mean and 90th percentile together to fairly evaulate distribution.
I think the reason it's so popular currently is that it's easy to describe (hence sell) and fits normal use reasonably well, so from a "normal buyer's" perspective is OK. Just as long as everyone is honest. Absolutely. Here's a scheme that, if everyone was using only 95th
On Fri, 20 Apr 2001 Toby_Williams@enron.net wrote: percentile billing, would give you webhosting at gigabit rate while only paying 30x minimal rate webhosting: a) colocate hardware at 30 different datacenters at gigE speed, but billed for 95th percentile. b) have a DNS server that rotates records, pointing to a different server each day. c) bingo. Each of your providers will remove highest 95th percentile (1.5 days worth of traffic) and only bill you for minimal utilization. -alex