Re: Growing RAID10 with active XFS filesystem

[Emmanuel Florac <eflorac@intellique.com>]

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Le Sun, 14 Jan 2018 21:33:17 +0000
"Wol's lists" <antlists@youngman.org.uk> écrivait:

> On 12/01/18 14:25, Emmanuel Florac wrote:
> >> My point is that all this causes geometries to change, and ext and
> >> btrfs amongst others can clearly handle this. Can XFS?  
> 
> > Neither XFS, ext4 or btrfs can handle this. That's why Dave
> > mentioned the fact that growing your RAID is almost always the
> > wrong solution. A much better solution is to add a new array and
> > use LVM to aggregate it with the existing ones.  
> 
> Does the new array need the same geometry as the old one?

That's the best way to preserve performance, yes.
 
> What happens if my original array is a 4-disk raid-5, and then I add
> a 3-disk raid-5? Can XFS cope with the different optimisations
> required for the different layouts on the different arrays?

No because your array will remain optimised for the initial layout.
However, if you add a new array with the same stripe characteristics you
should at least NOT lose performance. See also the mount options  Stan
mentioned earlier :)

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