Re: [PATCH 04/16] DRBD: bitmap

[Neil Brown <neilb@suse.de>]

On Tuesday May 5, lmb@suse.de wrote:
> On 2009-05-03T15:21:41, Neil Brown <neilb@suse.de> wrote:
> 
> > As I said, I don't immediately see the benefits of the activity log
> > format, however,
> >  1/ I am happy to listen to its benefits being explained
> >  2/ If we were to agree that merging DRBD functionality into md
> >    (for which there isn't a concrete proposal, but the suggestion
> >     seems to be floating around) were a good thing, I don't have any
> >     problem with supporting an activity log in md in the name of
> >     compatibility.
> 
> So, let's take a step back here.
> 
> All of this is extremely beneficial discussion to be had. As some of you
> are (painfully, sometimes ;-) aware, I'm a big fan of converging RAID
> implementations/back-ends, and the goal is well received.
> 
> But this will take a while, and both drbd, md, md/nbd, or even dm-raid1
> have large existing user bases, and HA environments don't switch easily.
> All are actively maintained.
> 
> Sharing more and more of the code strikes me as a mid-term goal, and
> full converges as a long-term one (alas).
> 
> What I think this argument has shown that drbd's design is sound (even
> if some choices, like that of the alternatives, are up for discussion),
> similar to different file systems (of which we seem to have plenty
> too).
> 
> I would suggest at this time, we may want to refocus on the remaining
> objections to merging drbd as a driver in the short-term.

I cannot imagine that there would be any.  Given its history, its
popularity, and its modularity, there can be no question about merging
it, and only a possible question on whether it should spend some time
in 'staging' first.
I doubt there is much call for that, but nor it is clear to be how the
decision would be made.

> 
> I think I've not read anything in the last 3-5 days which still would
> rate as a reason for rejection or delay.
> 
> Did I miss something?

This is lkml - no one can catch everything :-)

I big part of why I was comparing and contrasting DRBD to md is
because that enables me to understand it better.  That sort of in-depth
understanding is, for me, a prerequisite for an in-depth review.

So it is all just part of the review process....

NeilBrown