Explanation/Reference:

vamar, has a rather nifty technology called Sticky Byte Factoring which allows it to identify the changedinformation inside a file by breaking the file into variable length objects, this leads to much greater efficiencythan fixed size approaches as changes made early in a fixed length sequence affect all subsequent blocks/chunks/objects/whatever in that sequence. This in turn changes all the fingerprints taken following the changeddata which means you end up with a lot of new blocks/chunks/objects/whatever even if the data really hasn'tchanged all that much. Sticky Byte Factoring on the other hand can tell what exactly has changed, not just thatthings have changed.