Explanation use of Mbits 95%
What is an Mbit?
A Mbit is a unit which is used to measured data traffic when purchasing a colocated
or dedicated server
. Generally, we always talk about Mbit/sec, or Mbit per second.
If you have a fast connection at home, that's probably about 8 Mbit/s download and 1Mbit/s upload. If someone would download something from your PC, you're uploading. The maximum speed this "visitor" retrieves files is 1 Mbit/second. 1 Mbit/second is equivalent to 128 KB/second. You understand that this is painfully slow, especially if 10 or more people at a time do this. This is the reason why you do not want to host your website on your own connection.
In the data center, the connection to the server is 100 Mbit / second. The limit would thus lie at 12.5 MB per second. It is not difficult to understand that this is rarely achieved, however, if that is the case then we can put the server on a Gbit switch with a tenfold rate.
When purchasing data traffic in Mbits there are some things to keep in mind:
The number of Mbits that you are buying is not the limit but 95% of the average, measured over 30 days. See the section "How is it measured?" below for more information. This means that you are not limited in terms of speed, you can buy 1 Mbit and still have peak traffic to 100 Mbit should that be necessary.
How is it measured?
95% of the highest measured consumption is being charged, or: 5% highest peaks fall away. Luckily, you don't have to calculate it yoursel, the switch where your server is connected to keeps track.
The switch calculates how much the average use per 5 minutes was, and saves it as a measuring point. So each day you get 24 * 12 = 288 points. Per month (assuming 30 days) this is 8640 measure points.
All these points of averages are sorted from largest to smallest. The 5% highest points are removed. The highest measurement which then follows is the number Mbit you pay.
In other words: If your server is hotlinked by a heavy traffic website and you have a huge spike in traffic, you can cross off half day (5% a month!) traffic; if you would pay per GB, you would have to pay this traffic, with mbits you don't!
Mbit graph of a server with good spread but little traffic!
Mbit graph of a server with low distribution, but a lot of traffic!
Just a small example calculation with 20 measure points, instead of 8640.
Suppose the measure points are 3, 10, 5, 5, 4, 3, 3, 4, 5, 4, 5, 5, 4, 4, 4, 5, 4, 2, 1, 4
Sorted by value::
5% of the number of measurement points (20) is 1. The peak of 10 in this case falls off, and 5 Mbit is charged.
So, how many GB do I get out of 1 Mbit?
It is impossible to tell. Theoretically, the maximum is approximately 320 GB (depending on the number of days in the month) per month. This is, however, only possible at 100% flat traffic, which of course no webserver has.
At an average web host server we get between 160 and 220 GB traffic per Mbit.
The 5% highest peaks fall off.
The flatter your traffic (ie equal daytime traffic, but at night too!), the more GB you get from 1 Mbit.