Messages in this thread | | | Date | Sat, 19 Sep 2009 16:56:15 -0700 | Subject | Re: [GIT PULL] DRBD for 2.6.32 | From | Dan Williams <> |
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On Sat, Sep 19, 2009 at 3:02 PM, Lars Marowsky-Bree <lmb@suse.de> wrote: > On 2009-09-19T14:14:30, FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> wrote: > >> I guess that Christoph is worry about adding another user interface >> for kinda device management; once we merge this, we can't fix it (for >> the raid unification). > > Why can't it be fixed? > > Either > > a) there's going to be a transition period during which the "old" > interface is supported but depreciated and scheduled to be removed (all > driving the new unified same back-end), > > or b) there's going to be a new kernel which requires new user-space > tools sharp. > > In either case, dm/md are affected by this, so a third interface doesn't > really make much difference. The refactoring needs to happen in the > back-end anyway, and that actually becomes easier when all concurrent > implementations are present and can be reworked at the same time.
It's actually four "raid" implementations in the kernel if you count the multiple-disk functionality of btrfs. The precedent is already set for merging new multiple-disk management interfaces.
Neil has come the closest to actually trying to start (i.e. code) the unification effort [1] and that was for the relatively straightforward case of mapping the dm-raid5 backend to md-raid5... no uptake to date. There are no strictly equivalent drbd-backends in the kernel presently, so leaving this out of tree is a net-loss for mainline.
-- Dan
[1]: http://marc.info/?l=dm-devel&m=124567352518676&w=2
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