Ceph

Original report, from https://pad.ceph.com/p/Report_Documentation_Bugs
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https://docs.ceph.com/en/quincy/rados/operations/erasure-code-shec/
c={durability-estimator}
Description
The number of parity chunks each of which includes each data chunk in its calculation range. The number is used as a durability estimator. For instance, if c=2, 2 OSDs can be down without losing data.
This definition is inconsistent with the definition introduced by the original paper. It looks like (in ceph's implementation of SHEC) the corresponding parameter represents the local parity coverage (of #data chunks). The correct formula should be c (durability estimator) = ml/k. By the way, the implementation of SHEC of encoding matrix seems also different to what the paper suggests.
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Relevant information about SHEC (Shingled Erasure Coding): https://tracker.ceph.com/projects/ceph/wiki/Shingled_Erasure_Code_(SHEC)