On Sun, 6 Aug 2000, Carlos Carvalho wrote:

>Does this patch allow raid5 over raid0? That'd be really wonderful...

Despite it's useful nor not, which 2.?.x?

In 2.2.x that's not possible but for _very_ silly reasons.

Raid0 in general is a no brainer and fully transparent layer that we can
place anywhere/anytime we want, definitely also behynd raid5. Fixing this
in 2.2.x is ugly (it's just ugly enough supporting LVM (lvm does linear
and raid0) on top of RAID{[015],linear} ;). (note the other way around
doesn't work for the same silly reasons raid5 on top of raid0 doesn't
work) Other raids (1/5) that needs to generate additional requests are a
little bit more problematics though.

On 2.4.x we now have a modular and recursive make_request callback, that
will allow us to handle all the volume management layering correctly (so
if raid5 on top of raid0 isn't working right now in 2.4.x send a bug
report ;).

Andrea

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