Re: LVM root?

[Goswin von Brederlow <brederlo@informatik.uni-tuebingen.de>]

Lennart Sorensen <lsorense@csclub.uwaterloo.ca> writes:

> Well the documentation for LVM certainly said there was no way to keep
> the stripe setting if you added more disks to a VG.  Only the initial
> set could have a stripe setting.  After all the striping was based on
> what disks where available initially, and divided among them.  If you
> add more volumes later, it would be silly to force it to rearrange all
> your data just to stripe it across the new PVs.  Maybe they added such
> an option for people to be silly.  Not imposible to do after all, just
> seems silly.

Striping is something LVM does on a LV basis. When you create the LV
you set the number of stripes, which can be less than the number of
PVs. The number of stripes obviously can't just change when you add a
PV to the VG.

But according to the manpage when you change the size of a striped LV
it will by default use the same number of stripes for the new segment
or whatever you specify with --stripes. So you need free space on
enough PVs to extend a striped LV with the same striping. A single new
PV won't do it.

One thing missing is support in pvmove to change the striping of an
existing segment so you could change it from say 3 to 4 stripes when
you add a new PV. Seems like you want that.

> --
> Len Sorensen

MfG
        Goswin