On 07/11/2012 04:30 PM, Gregg Wonderly wrote: > This is exactly the issue for me. It's vital to always have verify on. If > you don't have the data to prove that every possible block combination > possible, hashes uniquely for the "small" bit space we are talking about, > then how in the world can you say that "verify" is not necessary? That just > seems ridiculous to propose.
Do you need assurances that in the next 5 seconds a meteorite won't fall to Earth and crush you? No. And yet, the Earth puts on thousands of tons of weight each year from meteoric bombardment and people have been hit and killed by them (not to speak of mass extinction events). Nobody has ever demonstrated of being able to produce a hash collision in any suitably long hash (128-bits plus) using a random search. All hash collisions have been found by attacking the weaknesses in the mathematical definition of these functions (i.e. some part of the input didn't get obfuscated well in the hash function machinery and spilled over into the result, resulting in a slight, but usable non-randomness). Cheers, -- Saso _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
