It is a sub-feature of the allocation classes you mentioned in your first email.
One of the options is to have an vdev dedicated to housing the DDT. On 2019-07-07 11:03, Richard Elling wrote: > Yes, from the ZoL zpool man page: > A device dedicated solely for deduplication tables. > > -- richard > > > > On Jul 7, 2019, at 5:41 AM, Stilez <[email protected] > <mailto:[email protected]>> wrote: > >> "Dedup special class"? >> >> On 6 July 2019 16:24:27 Richard Elling >> <[email protected] >> <mailto:[email protected]>> wrote: >> >>> >>> On Jul 5, 2019, at 9:11 PM, Stilez <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>>> I'm one of many end-users with highly dedupable pools held back by >>>> DDT and spacemap RW inefficiencies. There's been discussion and >>>> presentations - Matt Ahrens' talk at BSDCan 2016 ("Dedup doesn't >>>> have to suck") was especially useful, and allocation classes from >>>> the ZoL/ZoF work will allow metadata-specific offload to SSD. But >>>> briad discussion of this general area is not on the roadmap atm, >>>> probably bc so much else is a priority and seems nobody's stepped up. >>> >>> In part because dedup will always be slower than non-dedup while the >>> cost of storage continues to plummet (flash SSDs down 40% in the past >>> year and there is currently an oversupply of NAND). A good starting >>> point for experiments is to use the dedup special class and report >>> back to the community how well it works for you. >>> >>> -- richard >>> >> > *openzfs <https://openzfs.topicbox.com/latest>* / openzfs-developer / > see discussions <https://openzfs.topicbox.com/groups/developer> + > participants <https://openzfs.topicbox.com/groups/developer/members> + > delivery options > <https://openzfs.topicbox.com/groups/developer/subscription> Permalink > <https://openzfs.topicbox.com/groups/developer/Td9c7189186fd24f2-Mf90f2c92931dd028277934cd> > -- Allan Jude
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