_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.
In a thirty day billing period 95th%ile gives you one and a half days of *free
bandwidth*. 90th%ile gives you three days of *free bandwidth*.
From the seller's perspective, once this starts getting gamed a little more I
can't see it having much of a shelf life, and more sophisticated billing will
surface, similar to the power industry Sean sites.
I'm quite surprised we're not there already.. has anyone started venturing down
this route yet? (other than flat rate)
toby
Absolutely. Here's a scheme that, if everyone was using only 95th
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
c) bingo. Each of your providers will remove highest 95th percentile (1.5
days worth of traffic) and only bill you for minimal utilization.
But it's likely that 30 x minimal utilization is far more than one time all
the traffic. Bingo! Perfect shot! Not taking into account 30 x the hardware
and 30 x maintenance ...
-alex
Arnold
[ On Friday, April 20, 2001 at 09:57:55 (-0400), Alex Pilosov wrote: ]
Subject: Re: What does 95th %tile mean?
Absolutely. Here's a scheme that, if everyone was using only 95th
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.
Since you're probably going to get billed a port charge, and probably a
few other fees for each installation (not to mention installation
costs), that scheme will probably still end up costing you more than you
can save by simply finding the best bulk pricing from one or two
providers, and each provider will still make more from you in terms of
flat average usage than you actually use.
Sure each hosting site will experience one "bad" day per month due to
your "burst", but that's not going to hurt them too much. Eventually
they'll spot what you're doing too (at least if it hurts them at all)
and they'll probably force you to re-negotiate to a bulk-throughput
deal.
Besides if bandwidth is your biggest cost then you're going to have to
have at least two sites online at any given time and so you'll need 60
or more sites! The maintenance costs alone might kill you.
No sane person will try to play those games because they know they'll
end up paying one way or another. Either they'll get caught and be
forced to re-negotiate on byte counts (or move and face installation
charges again) or they'll end up paying way too much in capital costs
and service fees, maintenance, etc.