Hi Benoît, From the ( naïve ) point of view of engineering, performances are important. The recent works of James Plank ( cc'ed ) greatly improved them and I'm looking forward to the next version of jerasure ( http://web.eecs.utk.edu/~plank/plank/papers/CS-08-627.html ). Rozofs Mojette Transform implementation ( https://github.com/rozofs/rozofs/blob/master/rozofs/common/transform.h & https://github.com/rozofs/rozofs/blob/master/rozofs/common/transform.cc ) does not seem to make use of SIMD. Is it because the performances are good enough to not require them ? Cheers On 06/16/2013 09:51 PM, Benoît Parrein wrote: > Paul Von-Stamwitz <PVonStamwitz <at> us.fujitsu.com> writes: > > Hi Paul, > >> >> Loic, I know nothing about Mojette Transforms. From what little I gleaned, > it might be good for repair >> (needing only a subset of chunks within a range to recalculate a missing > chunk) but I'm worried about the >> storage efficiency. RozoFS claims 1.5x. I'd like to do better than that. >> >> All the best, >> Paul >> > > If you want to do better than that you will probably lose in availability. > 1.5x give the same availability than 3 replicats and that for any kind of > erasure coding. > FYI, Mojette transform has no constraint in terms of Galois fields. It is the > big advantage to use discrete geometry rather than algebra. > > best regards, > bp > > > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Loïc Dachary, Artisan Logiciel Libre All that is necessary for the triumph of evil is that good people do nothing.
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