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Re: [linux-lvm] raid and lvm



Am Die, 2003-01-28 um 18.34 schrieb SI Reasoning:

> I was following an old list and at that time they felt that it would be
> more efficient to merge either lvm into raid or vice-versa.

Yes. I've looked into the DM code in the kernel and I have to say it's a
very clean architecture. Since LVM2 needs some kind of Raid 0 (a
transparent mirror in the background) to implement pvmove it would be a
code duplication.

Also since DM has a nice plugin architecture and already has generic bio
splitting code, it would even save some memory when the raid drivers
would be reimplemented as DM plugins. (so the bloat argument doesn't
count)

Also you don't need the extra meta data the raid code actually has (ok,
raid autodetection won't work anymore but as far I understand the kernel
developers, that's depracted anyway). I've had problems with the raid
metadata code that could have been solved with things like vgexport and
vgimport.

But I think that's going to be adressed via the new in-kernel
initramdisk anyway.

And I think that the performance is better when raid is implemented in
DM than to run one device mapper over another one.

-- 
Christophe Saout <christophe saout de>




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