On Fri, January 7, 2011 14:33, Robert Milkowski wrote: > On 01/ 7/11 02:13 PM, David Magda wrote: >> >> Given the above: most people are content enough to trust Fletcher to not >> have data corruption, but are worried about SHA-256 giving 'data >> corruption' when it comes de-dupe? The entire rest of the computing >> world >> is content to live with 10^-15 (for SAS disks), and yet one wouldn't be >> prepared to have 10^-30 (or better) for dedupe? >> > > I think you are do not understand entirely the problem. [...]
I was aware of all of that. > Now what if block B is a meta-data block? > > The point is that a potential impact of a hash collision is much bigger > than a single silent data corruption to a block, not to mention that > dedup or not all the other possible cases of data corruption are there > anyway, adding yet another one might or might not be acceptable. And my point is that people are walking around the file hierarchy tree completely "blind" for most other file systems and are not worry about it all. They could be grabbing inappropriate data at a rate that is several orders of magnitude more likely than a hash collision and sleeping fine at night, and yet are worried about something that is 10^-20 less likely. Personally the potential impact of being hit by lightening is much bigger to me than anything that happens in at my job, and the odds of that are about 1 in 170,000 (2^-17 to 2^-18). If I'm not worried about that, why the hell should I be worried about something that is 2^-128? If then-Sun/now-Oracle thought it was a problem they wouldn't have made "on" an alias to "sha256". _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
