On Tue, 11 Dec 2012 12:08:12 +0000
Neil Bothwick <n...@digimed.co.uk> wrote:

> On Tue, 11 Dec 2012 12:48:13 +0100, J. Roeleveld wrote:
> 
> > > I'm using metadata version 1.2 for the raid0 array and the type is
> > > kernel based autodetect.  
> > 
> > Ouch, auto-detect does not work with metadata 1.2.
> > Please read the man-page section:
> > 
> > Please rebuild the raid-device using v0.90 metadata and try again.
> 
> I don't understand why your using RAID at all. LVM on top of RAID0
> makes no sense to me when you can simply make each device a PV and
> add it to the VG. That's more flexible and easier to repair.
> 
> 

Some folks like to do the striping in RAID, it's more controllable. 1st
block on this disk, 2nd block on that disk, 3rd block on first disk
again...

Pooling LVM PVs into a VG is a huge gigantic basket of stuff where you
don't really get to control very much - LVM sticks data wherever it
wants to and you do little more than give some gentle hints (which
I strongly suspect are mostly ignored)

But yes, in the usual case RAID-0 on LVM doesn't make much sense for
most folks.

Personally, I prefer ZFS. This whole huge list of shit just goes away:

disk partitions
partition types
disk labels
worrying about if my block size is right
worrying if my boundaries are correct
PVs as different from VGs and LVs
VGs as different from PVs and LVs
LVs as different from PVs and VGs
lvextend && growfs to make stuff bigger
umount && shrinkfs && lvreduce && growfs && mount to make stuff smaller

I can now take a much simpler view of things:

"I have these disks, use 'em. When I've figured out the actual quotas
and sizes I need, I'll let you know. Meanwhile just get on with it and
store my stuff in some reasonable fashion, 'mkay? kthankxbye! I have
real work to do."

:-)


-- 
Alan McKinnon
alan.mckin...@gmail.com


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