Re: Future of md multipath

[martin f krafft]

also sprach Neil Brown <neilb@xxxxxxx> [2009.03.06.0632 +0100]:
> > I understand that dm-multipath is more favourable, but unless
> > there's a riskless way to convert mdadm multipath into dm-multipath
> > on old systems, I don't think we have the option of deprecating it,
> > unless deprecation lasts for several years.
> 
> Always the practical one, aren't you :-)

Goes with the territory. Debian does not need to make long term
support guarantees. They're inherent in our quality assurance,
security support, and chaotic organisation. :)

> I wonder how hard it would be to get mdadm to assemble a multipath
> using the 'dm' code rather than the 'md' code....
> Or to get the md layer in the kernel to hook in to the dm multipath
> implementation.

A migration isn't possible?

> I think it is probably worth putting in a printk now to say "You
> should probably be using dm-multipath".  But we probably do need
> to leave the code there for a while longer..

Maybe it would be possible to disable creation of new multipath
arrays, but still to support existing ones, insert the warning, and
quote a fixed deprecation date, say, 5 years into the future?

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