I was reading the following FDS paper:https://www.usenix.org/system/files/conference/osdi12/osdi12-final-75.pdfand it says that the the following hash function does not distribute things uniformly (instead it creates a binomial distribution):$$i = (hash(g + t)) \pmod n$$while the following did distribute things uniformly:$$i = (hash(g) + t) \pmod n$$Why does the above distribute things evenly while the other one doesn't?g = is the global UID for a blobt = tract number. (tract is the measure/units of reads and writes to a blob).n = is the number of tract servers or a multiple of the tract servers.hash = SHA-1 (according to the paper)Paper Reference:Title: Flat Datacenter StorageAuthor(s): Edmund B. Nightingale, Jeremy Elson, Jinliang Fan, Owen Hofmann, Jon Howell, Yutaka SuzueInstitution(s): Microsoft Research, Univeristy of Texas at Austin
Why does the following function distribute things in a binomial distribution?
distributed systems;hash;hash tables