The default erasure plugin in Ceph is the Jerasure plugin, which is a highly optimized open source erasure coding library. The library has a number of different techniques that can be used to calculate the erasure codes. The default is Reed-Solomon and provides good performance on modern processors which can accelerate the instructions that the technique uses. Cauchy is another technique in the library; it is a good alternative to Reed- Solomon and tends to perform slightly better. As always, benchmarks should be conducted before storing any production data on an erasure-coded pool to identify which technique best suits your workload.

There are also a number of other techniques that can be used which all have a fixed number of M shards. If you are intending on only having two M shards, then they can be a good candidate as their fixed size means that optimizations are possible, lending to increased performance.

In general, the Jerasure profile should be preferred in most cases unless another profile has a major advantage, as it offers well-balanced performance and is well-tested.