dedup table, is it data or metadata?
Posted: Wed Jun 08, 2016 11:11 amIs the dedup table regarded as "data" or "metadata", i.e. is it written once like data or twice like meta-data?
It's treated as metadata and additionally you can cause extra ditto copies with "zpool dedupditto=number" where number is >= 100 or is zero (the default); when the reference count for a table entry goes above number when number is nonzero, the (many-entry) record it's in will be ditto-copied (see zio_ddt_write() for details).
Don't do deduplication on ANY pool where ANY device in the pool has a nonzero seek time. You'll be sorry eventually.