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July 10, 2014 12:21 PM   Subscribe

Is it quicker to upload one file at a time than to upload two simultaneously?

I have a ye olde copper line broadband connection, which is a bugger because I regularly deal with massive files.

I'm delivering two files, each over 1GB, and they need to be uploaded by tomorrow morning.

I'm uploading the files to WeTransfer. If I set both going simultaneously, will the upload take noticeably longer than if I send them one at a time.

(Sorry if that's a completely idiotic thing to ask!)
posted by popcassady to Computers & Internet (6 answers total)
Oh I wrote some file transferring software once. In general you'll actual see faster total speeds with two streams simultaneously, since during the time that the source is waiting for acknowledgment, the other stream can move along. The exact right number of streams depends on the network but typically 8 or so maximizes the total speed. Of course great file transfer software like BitTorrent can take this into account and do it automatically, but WeTransfer is just HTTP so it probably can't do that.
posted by miyabo at 12:36 PM on July 10, 2014 [1 favorite]

No, both at the same time is fine. TCP basically fills up the tube and then backs off just a bit until the tube isn't overfull. It doesn't care if there is one file being uploaded or a hundred, when we're talking about big files like these.
posted by wnissen at 12:41 PM on July 10, 2014 [1 favorite]

This is something easy to test empirically, if you have any way of monitoring the upload speed from that site/app, or on your router(or with a "speedometer" piece of software, i use istat pro on my mac but there's tons of them).

Two CAN be faster if the service you're uploading them to caps upload speed per transfer, and allows more than one at a time(DOUBLE CHECK ON THIS, i've done this and then had it finish and one or both or more files goes "lol you were uploading more than one at once sorry deleted").

Like, run a test and see what your max upload speed is. Then start uploading one file. Is it going that speed? Now try two, is the total throughput faster?

There's a lot of variables here, and the only real way to find out is just to try. I generally found two sequentially to be faster when i had crappy DSL, but now that i have a beastly connection then multiple simultaneous uploads or downloads can be faster if a single one isn't utilizing the whole connection. But, try and find out. My FTP client when i had DSL would multiplex downloads and uploads like this, and it did usually seem to be faster... but FTP is weird anyways.
posted by emptythought at 12:44 PM on July 10, 2014

The bottleneck is your connection. Everywhere else is probably faster so sending 2Gb takes the same time whether it is one or two uploads because it all has to travel over your bit of wire.

Theoretically it should be faster to drive multiple uploads so as to overlap transmission to B with waiting for acknowledgement from A, but I doubt the difference is significant in this case. Is it possible to compress the files?
posted by epo at 12:50 PM on July 10, 2014

Erm, "one or two" --> "sequential or concurrent"
posted by epo at 1:30 PM on July 10, 2014

miyabo: In general you'll actual see faster total speeds with

Got any data? Like, 10% faster, 25% faster, 2% faster? At some point it's an interesting fact, but functionally useless.
posted by IAmBroom at 3:54 PM on July 13, 2014

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