How to download a single file in separate chunks with different computers in LAN

downloadlan

I have access to a LAN network with about 20 computers and I want to download a file with large size which will take ages to download with my current download speed ( 50 kilo-byte/s )
So, I am wondering if there were a way or software to use to download separate parts of the same file with different computers in order to finish faster.
Any help is appreciated.

Best Answer

Since you say that the limit is per computer, you can download the file in, say, ten chunks from ten computers.

Actually, I'd start downloading from one computer, then add another, and another... until I would notice that the actual download speed has fallen below the theoretical maximum rate allowed of 50 Kb/s. That would mean that the uplink is now saturated, and there's no reason to continue adding clients (actually, that would slightly decrease transfer efficiency).

To download a single piece of a file, you need a utility such as curl (curl.haxx.se)

curl -r 0-10000000 -o Block1.bin http://www.site.com/path/to/largefile.zip

this will download the first ten megabytes into Block1.bin.

If you already know in advance that you can use at most, say, seven clients, you divide the file length by seven and download seven large chunks. That will make optimum use of TCP connection. If you don't know the size, 10M is a reasonable chunk size: just keep monitoring the clients and start another download as soon as one is finished.

To reassemble the chunks, you can use cat. They say that COPY /B works as well in Windows, but I never dared. If you feel adventuresome, try

copy /b Block1.bin+Block2.bin+Block3.bin+... mylargefilereconstructed.zip

Important: whatever you say, if there is a 50K/s per PC policy, it means that bandwidth is at a premium and/or there have been bandwidth hogging problems. What you are doing now will recreate those problems, therefore you had better first clear this out with the network admins and maybe agree on some time frame to perform the download with minimum disruption to the network (at night, during lunch break, at weekends and so on). This could spell the difference between a quick download and a quick termination of your work position.

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