The Economist has published an article about the technical details on how Wuala is working.
The challenge is how to minimise the number of copies of the same file that have to be distributed. Copying costs participants both storage space and bandwidth. Yet there have to be enough copies to ensure that there is at least one available most of the time. If, for example, each computer is online 25% of the time, then a quick calculation shows that you would have to copy each file to 100 different computers to ensure that 999,999 times out of a million there is at least one copy available when a user looks.
But copying every file a hundred times is hugely inefficient. Instead, Mr Grolimund and Mr Meisser plan to break each file into chunks, which can be scattered liberally around the hard disks of participating computers, and then to use a mathematical trick to reconstruct the original file from those chunks.
This trick is called “Reed-Solomon error correction” and is actually used for CD/DVD/BluRay-Discs, DVB and DSL.
If you are interested in more details on how Wuala stores and distributes files, you should give the article a read.
Via [Slashdot]
