Web Hosting Talk : Web Hosting Main Forums : Colocation and Data Centers : Question about 95th Percentile

[tr0gd0r]

I have a question about 95th percentile billing. Say I have a 6mbit commit. That means I should be getting 2000GB/month. I calculated that if I burst 100mbit until I get 2000GB then do no bandwidth for the rest of the month, I would get charged for 100mbit of commit, is this correct?

Calculations

2000000MB * 8 = 16000000 mbits / 100mbit = 160000 seconds / 60 = 2667 mins / 60 = 44.4

So 44.4 hours of 100mbit equals 2000GB.

Now lets say they take a snapshot every 5 mins.

44.4 hours * 60mins = 2666 / 5 mins per snapshot = 533 snapshots

Now lets find the total number of snapshots in a month.

30 days * 24 hours * 60 minutes / 5 minutes per snapshot = 8640 snapshots

Now we find 95th percentile

8640 * .95 = 8208

8640 - 8208 = 432

So 432 snapshots will be dismissed as burst, but I will have 533 snapshots at 100mbit (as calculated above).

Is this correct?

Thanks

[KDAWebServices]

Roughly speaking, you get your highest 36 hours of usage for "free", so a quick glance would suggest you're pretty much on the money with your figures. 2000GB of data transferred is more like 10+Mbit/s for most people. We see 180-200GB/month on average per mbit of 95th measured bandwidth.

[KarlZimmer]

Originally Posted by KDAWebServices

Roughly speaking, you get your highest 36 hours of usage for "free", so a quick glance would suggest you're pretty much on the money with your figures. 2000GB of data transferred is more like 10+Mbit/s for most people. We see 180-200GB/month on average per mbit of 95th measured bandwidth.

Yep, our findings are the same, and I agree with everything you said. Karls unite!

As an example too, if you use 6 Mbit/sec 24/7 but 100 Mbit/sec for 36 hours you'd get 6 Mbit/sec on 95th but push ~3450GB in a month. Do the exact same thing inbound, and you get nearly 7TB of throughput on just a 6 Mbit/sec commitment.

[osopolis]

Originally Posted by KDAWebServices

Roughly speaking, you get your highest 36 hours of usage for "free", so a quick glance would suggest you're pretty much on the money with your figures. 2000GB of data transferred is more like 10+Mbit/s for most people. We see 180-200GB/month on average per mbit of 95th measured bandwidth.

Hi.

I have also heard that counting with the 95% methode, you can push ~ 200GB a month each "1 Mbit" of commitment. (so 2 Mbit would be 400GB).

My question is now: Can you use this way of calculation as a fix fakt?
Lets say I know I will need 3TB of traffic ... is that ALWAYS automaticaly ~15Mbit 95%? Or does "burst behavior" influence the total among of bandwidth you can acualy push. (In other words:Is 15Mbit on 95% always 3TB or can it be less if you have a big gap between peeks and normal usage)
How does it looks like if you are on a gig connection. Does the calculation chage?

thanks

[KDAWebServices]

Hi,

As I said in my post, we see 180-200GB month per Mbit for most customers, it varies depending on traffic profile - We've seen 70-80GB/mbit of 95th before now. At the end of the day, there is no fixed conversion, you should either be paying for bandwidth, or data transfer - and neither should be calculated from the other i.e. You buy 1000GB of transfer, but the supplier measures on 95th percentile and converts that to GB used with some fixed number of GB per mbit, or the other way around - As that's wrong.

[Blake32287]

Some carriers \ hosts have different policys. Wikipedia has a pretty good explanation...Cant post url's yet so cant link it, sorry.

[hhw]

Originally Posted by osopolis

Hi.

I have also heard that counting with the 95% methode, you can push ~ 200GB a month each "1 Mbit" of commitment. (so 2 Mbit would be 400GB).

My question is now: Can you use this way of calculation as a fix fakt?
Lets say I know I will need 3TB of traffic ... is that ALWAYS automaticaly ~15Mbit 95%? Or does "burst behavior" influence the total among of bandwidth you can acualy push. (In other words:Is 15Mbit on 95% always 3TB or can it be less if you have a big gap between peeks and normal usage)
How does it looks like if you are on a gig connection. Does the calculation chage?

thanks

The calculation between data transfer and 95th percentiile can be highly variable, depending on your traffic patterns, and the type of connection you have. If your bandwidth is absolutely constant, 3TB could be under 10Mbps.

If your traffic is erratic, it could be anywhere. If you're on a gigabit link, 3TB of traffic could be free as you could do all of your transfer for the month in under 36 hours, and do no traffic the rest of the time. Then again, if you do all your traffic in roughly 37 hours of the month, you could be doing as much as 185Mbps of traffic. On a 100Mbps connection, it won't be quite as variable, but you could be anywhere between 10Mbps and 100Mbps.

There are of course the extreme cases. You best bet is to look at your current graphs, and project what your future requirements will be like based on that. If you're really concerned about your bandwidth levels, use average sustained billing for a few months and calculate your 95th percentile based on those few months.

Of course, you will always want to keep an eye on your graphs, or even better yet, setup alerts if your bandwidth exceeds certain levels.

[tr0gd0r]

Hosts will let me choose between "average sustained" and 95th?

Is that true?

[hhw]

Depends on the host, but there are definitely ones out there who offer both billing methods. Even if it's not explicitly offered, you may be able to negotiate a deal.

[osopolis]

Thanks hhw.

I am about to register my own ASN and need 2 uplink providers. Unfortunately
none of them offer average on a gig link. They all want the 95% pay methode.
My graph looks pretty "constant" so far but the market kinda forces you to offer "more bandwidth" at low costs.

It is difficult for me to predict how the graph will be in the future (are there going to be 2 or more power customers having their "peek" time at the same time?)
It is a more difficult calculation methode in a "merchant" way.

cheers

[relichost]

It's a risk you take, there's no way around it short of going to average billing, but this usually incurs a large fee.

[KarlZimmer]

Originally Posted by osopolis

Thanks hhw.

I am about to register my own ASN and need 2 uplink providers. Unfortunately
none of them offer average on a gig link. They all want the 95% pay methode.
My graph looks pretty "constant" so far but the market kinda forces you to offer "more bandwidth" at low costs.

It is difficult for me to predict how the graph will be in the future (are there going to be 2 or more power customers having their "peek" time at the same time?)
It is a more difficult calculation methode in a "merchant" way.

cheers

I don't know of any major carriers offering per GB/average sustained billing models period, let alone on gigabit links. You'll definitely be paying in 95th, which is then why it is less of a risk for providers to offer their bandwidth using the same billing scheme.

If you want to proceed, you need to look to see if that is a risk you're willing to take, if not I'd recommend going with a single colo provider and not running your own network. otherwise, depending on your traffic patterns, and InterNAP FCP might be able to assist with balancing your traffic between the two lines, keeping your overages at a minimum, etc.