I back up the servers at my colocation in Cheltenham, to here. Sometimes, that means that I have to shift a *lot* of data, and my main line is only 2 megabits, which means about 0.9 gigabytes per hour.
However. I also have three DSL lines, and they're fast for downloading; I get 6 to 8 megabits, which lets me backup at about three gigabytes/hour.
But sometimes, even that isn't fast enough. Is there a way I can download using all three lines?
Apparently not, unless I do something excessively clever called "bonding" using hardware I don't have, to combine the lines into a single channel. But I've found another way.
I set up three computers to use the three DSL IP addresses as their gateways. That means that anything I download to those computers, comes down at the DSL speed of 3 gb/hour.
But then, how to combine them?
The answer is Samba. Let's call the computer that's receiving the backup BoxA, and the other three are BoxB, BoxC and BoxD. First, I need to run the Samba server on BoxA, sharing the directory that I'll be backing up to.
Then I mount that directory on the three other boxes. I work out what stuff is going to need to be downloaded, and I set each of the three boxes to download different parts of that. This gives me a total of 9 gb/hour.