Alex Elsayed wrote: > Loic Dachary wrote: > >> Hi Ceph, >> > <snip> >> Reed-Solomon coding family is the only one that can keep the chuncks >> unencoded and therefore concatenable. > <snip> > > In my understanding, this is not strictly true - any 'systematic' code > will have the unencoded chunks remain available in this manner, and any > non- systematic linear code can be transformed into a systematic code with > the same minimum distance. Fountain codes are often explicitly constructed > to maintain this property, as in the case of RaptorQ [RFC 6330]. > > https://en.wikipedia.org/wiki/Systematic_code ...that said, Reed-Solomon is to the best of my knowledge the only space- optimal such code. An interesting option, however, might be to use a fountain code over the network when distributing either replicas *or* parity chunks, so that losses can be recovered with <1 full chunk retransmission. -- 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
