Am I computing transfer speeds wrong?

N

nomar

[H]ard|Gawd
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Jan 30, 2002
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I'm editing an article comparing transfer speeds of certain products and the data is as follows:

File size: 2,125,725,696 bytes

Average transfer time over the network was 2:37.85

So by my calculations, 2125725696 is 16218 megabits. Right?

So 16218 megabits transferring in 157.85 seconds is 102.7 mb/s right? How can that be on a network with a theoretical maximum speed of 100mb/s which we all know you can't attain?

Am I confusing something?
 
Your math is not incorrect.

My question would be, what type of file is it? Dial up networking at the least will automatically compress certain files (text files or BMP's for example) when sending. So you could be sending someone a BMP back in the dial-up days, and it would say you were sending at some near miraculous speed, like 10-15k per second, because the file was actually being compressed automatically.

Perhaps this is what's happening in your case. What type of file was it?

I would suggest attempting the test again, with a large ZIP file at maximum compression so that you know compression isn't a factor.

Erik
 
I'm not exactly positive what the file was - the writer said that it was a binary image of a partition. Often drive images are compressed aren't they?

I'm correct in saying that ALL transfer speeds are expressed in megabits per second right? ATA133 is 133 megabits per second... SATA is 150 megabits per second... 10/100 ethernet is 10 or 100 megabits per second.
This is testing the transfer speed from a computer on a network to the server. The test was done 10 times and the average was the 2:37.85. Maybe the tester is not timing it accurately?

Interesting theory about compression Dem.

I have been doing my own testing for wireless network transfer speeds and I have been using the .zip file for the FarCry demo. Is that a bad file to use? It is 508.833MB.
 
Just to add more to this... I guess using a random file and timing it is not the best way of calculating a true transfer speed.

Isn't there a command prompt entry that does this?
 
I would look at highly compressed files, and just use the same one over and over, so your comparing apples to apples. Imaged files are compressed, but like zip files, you can choose the level of compression... Higher compression on the files means less possible compression from the protocol/adapter.
 
Originally posted by nomar
I'm not exactly positive what the file was - the writer said that it was a binary image of a partition. Often drive images are compressed aren't they?

I'm correct in saying that ALL transfer speeds are expressed in megabits per second right? ATA133 is 133 megabits per second... SATA is 150 megabits per second... 10/100 ethernet is 10 or 100 megabits per second.
Click to expand...
ATA 133 is 133 megaBYTES per second.
ethernet is in megaBITS though.
 
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