[Drbd-dev] [GIT PULL] DRBD for 2.6.32

FUJITA Tomonori fujita.tomonori at lab.ntt.co.jp
Wed Sep 23 13:36:32 CEST 2009

On Tue, 22 Sep 2009 08:20:34 +0200
Lars Marowsky-Bree <lmb at suse.de> wrote:

> On 2009-09-22T07:27:21, FUJITA Tomonori <fujita.tomonori at lab.ntt.co.jp> wrote:
> > > If it happens, once that happens, that _will_ be an ABI break.
> > 
> > You misunderstand the raid unification.
> > 
> > We will not unify the kernel<->userspace configuration interface
> > because we can't break the kernel<->userspace ABI.
> I disagree here. Who says we can't over time, and with due notice?
> For sure, the new ABI needs to co-exist with the old ones for a while,
> until it is proven and fully complete, but then, why can't the old one
> be marked as depreciated and phased out over 1-2 years time?

Let me know If you find a Linux storage developer who say, "Yeah, we
can remove the md ABI over 1-2 years time after the raid unification".

Seems that you have a very different idea from other kernel developers
about the stable ABI.

> > We plan to unify the multiple device frameworks, but the unified
> > framework must support the all existing ABIs.
> > 
> > So adding another 'drbd' ABI hurts us.
> Even that doesn't really apply, I think. If the new framework is
> powerful enough and a super-set of everything that came before, the shim
> layer will be somewhat annoying, but harmless code.

Improving the existing framework is a proper approach.

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