erasure code and coefficients

[Loic Dachary <loic@dachary.org>]

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Hi Andreas,

In http://anrg.usc.edu/~maheswaran/Xorbas.pdf I get the idea of computing local coding chunks the way it is implemented in https://github.com/ceph/ceph/pull/1921 (i.e. delegating encoding / decoding to other plugins). However, there are theoretical aspects of the paper that I do not understand and I'm hoping you can shed some light on it. In particular, I don't know what "coefficients" are about. For instance in the context of Figure 2 caption : "The main theoretical challenge is to choose the coeffi\x0ecients c(i) to maximize the fault tolerance of the code."

Would you recommend a paper to read to better understand this ? Also I'd like to understand what "coefficients" mean in the context of jerasure or if they do not apply.

Thanks for you help :-)

-- 
Loïc Dachary, Artisan Logiciel Libre


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