Comment by ryao
Hearing that it is missing some code for reconstruction makes it sound like it is missing something fairly important. The original purpose of parity RAID is to support reconstruction.
Hearing that it is missing some code for reconstruction makes it sound like it is missing something fairly important. The original purpose of parity RAID is to support reconstruction.
We can do reconstruct reads, what's missing is the code to rewrite missing blocks in a stripe after a drive dies.
In general, due to the scope of the project, I've been prioritizing the functionality that's needed to validate the design and the parts that are needed for getting the relationships between different components correct.
e.g. recently I've been doing a bunch of work on backpointers scalability, and that plus scrub are leading to more back and forth iteration on minor interactions with erasure coding.
So: erasure coding is complete enough to know that it works and for people to torture test it, but yes you shouldn't be running it in production yet (and it's explicitly marked as such). What's remaining is trivial but slightly tedious stuff that's outside the critical path of the rest of the design.
Some of the code I've been writing for scrub is turning out to also be what we want for reconstruct, so maybe we'll get there sooner rather than later...