On Sat, Sep 14, 2013 at 04:13:41PM +0000, hru...@gmail.com wrote: > Marc Espie <es...@nerim.net> wrote: > > > On Sat, Sep 14, 2013 at 03:09:48PM +0000, hru...@gmail.com wrote: > > > > > A completely other thing is to conclude that two *arbitrary* pieces of > > > data are the same only because they have the same hash. Arbitrary > > > means here that the one was not a copy of the other. And this is what > > > rsync seems to do as far as I understand the wikipedia web-page. > > > > The probability of an electrical failure in your hard drive causing > > it to munge the file, or of a bug in the software using that file > > is much higher than this happening. > > This is a conjecture. Do you have a proof that the probability is so > small? For me it is difficult to accept it. Is this conjecture used > elsewhere?
Oh, for crying out loud. There's a REPORT included with rsync, that describes the algorithm. Rsync uses 128 bits checksums to ensure files are not corrupted. The 16 bit checksums are just for *identifying blocks for transfer*. The end check is *of course* a full checksum. I consider 1/2^128 to be *vanishingly small*. It's ways more likely for a cpu or memory bug to occur. Cosmic ray radiation, or something, which you generally don't consider to be a big problem, is ways more probably to affect your memory, and storage. > I dont like rsync and similars!!!! Just because you're irrational doesn't mean we have to cater to your irrational fears.
