On Fri, Jun 19, 2020 at 01:04:03AM -0400, Zygo Blaxell wrote: > It might be nice to keep btrfs-dedupe and bedup _somewhere_ on the wiki, > clearly marked as not supported and only of historical interest to new > developers. I learned a lot about what is possible on btrfs from bedup > in particular (bees was initially a project to combine the features of > bedup and duperemove), and python is accessible to more developers than > C or C++. btrfs-dedupe was the first btrfs dedupe agent to combine > defrag and dedupe operations into a single program. It's there now. > > So I do agree with waxhead. It would be preferable if there were an > > official btrfs deduplication command from btrfs-progs instead of relying on > > 3rd parties. Joe Bloggs example above can read a web-page instructions > > saying "run this command... and then this command..."; but he will not have > > the knowledge, nor comprehension nor time to go through code. > > Which of the available candidates for "official btrfs dedupe" would you > put in btrfs-progs? I see a lot of runners in the race, but no clear > winner yet. > > duperemove is the closest to Waxhead's proposed "-r /somewhere" syntax. > It's the obvious choice: written in the same language as btrfs-progs, and > also the oldest btrfs deduper, and it has years of patient, data-driven > optimization built in. That there's not even a simple eg. file-based deduper available in btrfs-progs is kind of bad. Duperemove is indeed closest to that. > If there wasn't some insurmountable reason > why duperemove can't be merged with btrfs-progs, then it would have > happened already, so there must be a reason why this can't ever happen > (which might be as simple as neither maintainer wants to merge). I'm not against adding the functionality to btrfs-progs, but merging whole duperemove feature set might not happen due to additional dependencies. This would need to be evaluated, but I'm not aware of any other technical reasons. I don't remember exactly why duperemove started as a separate project instead of a subcommand or progs, but we can revisit that. > Maybe we put duperemove at the top of the Wiki page, as it has the > simplest command-line for Joe Blogger's use case, and it's relatively > easy to build for the few people who use distros where it's not packaged. That's a good idea, a 'quick start' section, with description of most common usecases using duperemove. > The stub support for in-kernel dedupe (arguably the only "official" > btrfs dedupe so far) has been removed due to lack of interest in its > development. That _was_ available in branches of btrfs-progs > as 'btrfs dedupe'. It's gone now. The more I think about in-band dedupe (and how it would complicate everything), I'm leaning more towards a user-space solution with support from kernel (ioctls, keeping hashes of recently modified blocks but not doing the actual deduplication, reading hashes from csum tree, etc).
