[thelist] hosting (n00b)

[Kelly Hallman]

On Fri, 17 Oct 2003, Gavin Lilley wrote:
> We are allowed 16000 bytes/sec, this figure is burstable to 512 Kbps and
> we are allowed to exceed the 16000 bytes/sec 432 times without charge.

This is 95th-percentile billing. In other words, you're allowed to exceed 
the included bandwidth for 5% of the month (5% of the 5-minute samples). 
The top 5% of your bandwidth for the month is then discarded, and you're 
billed at the rate of the highest remaining sample.

So, if your 95th-percentile sample is 30k, then you will be billed as if
your bandwidth for the month was 30kbps. In other words, averages or total
transfer has little to do with it, other than the fact that the 5-minute 
samples themselves are averages for each 5-minute period.

This billing model may seem strange to some, but it's likely this is how
your ISP buys their bandwidth, regardless of the billing structure that
they present to their customers.

> In theory the bandwidth we are allowed is:
> (30*24*60*60)*16000 = 41472000000 bytes (39 Gig)
> Plus the additional burstable amount which is hardly worth a mention:
> (512-16)*432=214272

I don't know if that burstable bandwidth figure is accurate. That
bandwidth is not included, it's just available. If it turns out that you
are using over your 16kbps 6% of the time, you'll be billed for overage.

The overage charges may be significant. If your bandwidth really does
average 20-30kbps you may be better off buying a bigger pipe, at least
32k. With 95th-percentile, you're best off if you can estimate your 
requirements ahead of time--it's a numbers game.

> According to the MRTG graphs our bandwidth averages between 20-30 kb/s so
> taking the higher figure I calculate our bandwidth as follows:
> (30*24*60*60)*30=77760000 bytes

Again, I'm not sure that this sort of calculation really means anything, 
since it's likely the only thing that your ISP is going to look at is the 
value of that 95th-percentile sample. In theory, yes, you have about that 
much potential bandwidth. However, typical bandwidth patterns are not that 
predictable and it's unlikely you'll ever realize all that bandwidth.

By figuring the overage charges, you can decide if it's worth it to 
stay at the 16kbps level and pay the overages. It may be more economical 
to buy a pipe that keeps you within your allotted bandwidth more often.

-- 
Kelly Hallman
http://wrack.org/