WIP: doc/dev: add explanation of how to use deduplication

[myoungwon]

Signed-off-by: Myoungwon Oh [email protected]

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[anthonyeleven]

Please amend the PR and commit descriptions with the preferred format beginning with the full relative directory, in this case something like:

doc/dev: Add explanation of how to use deduplication

[athanatos]

Add a warning at the top that this feature is highly experimental and is subject to change or removal.

[anthonyeleven]

warning

Very good point.

[myoungwon]

@athanatos Can you take a look?

[zdover23]

@myoungwon: The "pull request checklist" wasn't filled out, which was preventing this PR from being mergeable.

I've filled out the checklist, and will now merge and backport this PR.

[zdover23]

https://github.com/ceph/ceph/pull/48567 - Quincy backport https://github.com/ceph/ceph/pull/48568 - Pacific backport

[athanatos]

@zdover23 This probably shouldn't be backported.

[zdover23]

@zdover23 This probably shouldn't be backported.

@athanatos: I'll create a couple of new PRs that take this feature out, since you're the architect of this thing and the authority on it. I acted here (wrongly, as it turns out) after consulting an email to [email protected] on 16 Apr 2020 with the subject line "CDS Pacific highlights - RADOS", which suggested to me (again, wrongly, which is totally on me) that this feature would be new in Pacific.

In short: sorry about that.

[zdover23]

@athanatos: Is deduplication expected to land in Reef?

[zdover23]

https://github.com/ceph/ceph/pull/48570 - Quincy backport reversion

[zdover23]

https://github.com/ceph/ceph/pull/48571 - Pacific backport reversion

[athanatos]

@zdover23 No worries, thanks!