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FTP speed limites for single file transfer


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simple problem, please assume both parties have sufficient network bandwidth and there is no obvious interference from other applications.

Server is using filezilla server to host a large 17gb file. Client, running filezilla, can only download this file at maximum 50% of their true download bandwidth. Nothing we tried helped this speed.

I split the file into 2 and let the client download both files simultaneously, each file downloads at about 50% max bandwidth which totals to the maximum and everything is peachy...

What's going on here? Why can't the 1 file download as fast as 2 files combined? Server and client have allowed unlimited transfer speeds.

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Off the top of my head, there's a setting in either the server configuration or the client configuration setting a maximum speed of 50% of the total bandwidth. Barring that, it's the ISP most likely.

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I know it's not the server and i doubt it's the clients. They are using default chrome, IE, and even filezilla. I assume the defaults don't have speed maximums per file.

You think it's the client ISPs? anyone aware of comcast or verizon fios limiting per file download limitations on ftp file transfers? <-- seems very unlikely.

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its not "per file" but per session would be where you would see limits.

Also you sure your tcpwindowsize is correct for your available bandwidth and RTT between this host your downloading from. This would also limit what you could download per session. Creating more sessions would allow for more bandwidth to be seen on your pipe if available.

What OS is your client?

We an get into the math if you want? But lets get some numbers to work with, what is the bandwidth provided by your ISP both up and down? Also what is the ping time to this ftp server?

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I can't find the setting in filezilla atm, but I remember by default it only displays the average transfer speeds, you have to change a setting to force it to show actual transfer speeds in realtime

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Server is a 100/100 connection. clients are on various connection speeds. 15/5 being the most popular. I am looking for the per session speed limitation options but haven't found it.

Also you sure your tcpwindowsize is correct for your available bandwidth and RTT between this host your downloading from. This would also limit what you could download per session. Creating more sessions would allow for more bandwidth to be seen on your pipe if available.

This makes sense, but I don't know how to adjust the tcpwindowsize. All machines are running windows 7.

Thanks for the tip about the interface speed displays. I think the server shows real time speeds by default so the problem still exists.

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If you give me the details in a PM, I will see what I can download at.. I have my settings correct - and once can ping server can work out what they should be for max throughput, etc.

PM the details and be happy to test for you.

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