Hi, It is possible for a bit-flip to change data that is to be written to disk after its hash has been computed, but before it has been sent to disk. This is primarily a concern for systems without ECC RAM.
It is possible to correct (some of) these errors by including some forward error correction bits in the hash (or, perhaps next to it, but we should include some FEC bits for the hash itself since it too could be corrupted). It wouldn't have to be more than a few bits, since we expect at most a bit flip or two for any given block of data. Would there by interest in such an extension? It is conceivable that a lot of redundancy could be useful: such a scheme could correct bad blocks on disk. This would primarily be useful on systems with just a single drive (e.g., a laptop) or when resilvering a mirror vdev and the remain disk has a block block (this, unfortunately has happened to me). Thoughts? (If this is the wrong place for such questions, please tell where to post instead.) Thanks! :) Neal _______________________________________________ developer mailing list [email protected] http://lists.open-zfs.org/mailman/listinfo/developer
