Messages in this thread | | | Date | Wed, 23 Sep 2009 20:27:51 +0900 | Subject | Re: [GIT PULL] DRBD for 2.6.32 | From | FUJITA Tomonori <> |
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On Mon, 21 Sep 2009 20:51:32 -0400 Kyle Moffett <kyle@moffetthome.net> wrote:
> On Mon, Sep 21, 2009 at 18:27, FUJITA Tomonori > <fujita.tomonori@lab.ntt.co.jp> wrote: > > On Mon, 21 Sep 2009 18:53:21 +0200 Lars Ellenberg <lars.ellenberg@linbit.com> wrote: > >> That's not what I meant, of course that is and needs to be stable. > >> Sorry, I exagerated to make a point. > >> > >> Point was: > >> mdadm configured md. > >> dmsetup configured dm. > >> drbdsetup configure drbd. > >> > >> If and when "something" is done to "unify" things on the implementation > >> level, it is likely to also unify the "kernel<->userspace" configuration > >> interface. > >> > >> 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. > > > > 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. > > One major issue for me personally (and I don't think its been mentioned enough): > > There is a *VAST* existing user-base for DRBD. Basically every vendor > builds the modules for their kernels, ships the userspace tools, etc. > *Regardless* of when or how it gets merged, the existing user-base > will need kernel support for the existing tools.
I don't think that the user base can be a reason for mainline inclusion.
IMHO, vendors should use their resource to push an out-of-tree thing into mainline instead of taking care of it with their own kernels. Finally, device-mapper people are trying to push the similar feature. I think that the history taught us that people who have used out-of-tree stuff eventually move in the mainline alternative.
> To put it another way: Would you really keep a stable SCSI raid > driver for existing hardware out of mainline by claiming they need to > write a new raid-management abstraction first? If not, then why the > pushback on DRBD?
Yeah, we should have done that. It's too late though.
Anyway, I don't think that your example is fair; we need a driver for scsi hardware but we have an alternative to drbd.
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