• 09/28/2015
    8:00 AM
  • Rating: 
    0 votes
    Vote up!
    Vote down!

Throughput 101: Don't Guess At File Sizes

In this video, network troubleshooting guru Tony Fortunato demonstrates how to perform a file transfer test to determine file size.

I enjoy calculating real throughput on real networks with real devices. In many cases, the easiest and most realistic test is a file transfer using SMB, FTP, HTTP, etc.

The main point of this video is to introduce you to basic testing best practices. For example, you should be using an ftp script or wget to keep the test consistent, take multiple measurements (in some cases at different times of the day), and approach the test with an idea of how long it should take. That way you immediately have an idea if you should investigate further.

The intent isn't to compare or debate if file copies are "better" than generating a stream like iperf. I'm simply showing you how to do the math and calculate either the file size or duration of a test.

I make a point early in the video that you should take my saying, “You are only as fast as your slowest link” literally. As I mentioned, in some cases the slowest link is not a network connection, but an interface in the computer. Examples include USB, Firewire, Inifiband, Fibre Channel, and SATA.

Enjoy your testing.



These good catchy lines of your blog makes me read your blog again and again.Apart from fact that throughput does not work when it comes to how to deal with protocol overhead, it is still oftenly/ frequently used term. On the other hand lets consider goodput which can help us in a ratio between delivered amount of information, and the total delivery time. But still we are not very much familiar about same...

Re: GoodPut

thanks for taking the time to share your thoughts.

i totally agree and am considering a followup article trying to take it a step further to define other terms.


slowest link

"You're only as fast as your slowest link" reminds me of the oft-used saying in security: "You're only as strong as your weakest link."

Re: slowest link

hey you're correct.  never occured to me.

Re: slowest link

Great video -- thank you for sharing it with us. As the world becomes more connected and a greater number of users come online, it is important that the average user also understands the difference between a Mbps and MB/s as it will help to grade and extract the full value from their DSL service, and avoid possible misunderstanding with their ISPs.

Download and upload speeds should also be taken into consideration as often times the average upload speed is 10 times lower than, the average download speed (depending on the technology and consumer requirements). At the one hand, this seems to be reversing economics at the individual level i.e. consuming data is cheaper than producing data. And on the other hand, in aggregate it makes sense for the service provider to create networks that favor download speeds because, the vast majority of the users are consumers of data. 


Re: slowest link

excellent point Brian.

thanks for taking the time to provide your feedback.