LVM not fit for default

[Andy Green]

Callum Lerwick wrote:

>> When LVM is inflicted on to situations that cannot benefit from it, the 
>> end result is you made something more fragile for no gain: that can't be 
>> right.
> 
> Every PV keeps duplicate copies of the metadata by default. You can
> optionally make it store three. Two at the start, one at the end. And
> every PV in a VG has a copy of the metadata as well. So with two PVs
> that's four copies of the metadata by default, and optionally 6.
> 
> ... And backing up your LVM metadata to your /boot partition isn't a bad
> idea either. As well as an offline backup.
> 
> So I have 11 copies of my LVM metadata. That seems rather redundant to
> me.

Sounds impressive, but the LVM that was damaged here was not visible nor 
mountable in Fedora, although the filesystem behind it was mostly intact 
and mounted okay when I had a copy of it without the LVM stuff in front 
of it.  Googling at the time didn't bring up anything about how to use 
these proposed copied of "metadata" nor was anything done about them or 
mentioned about them by the LVM stuff in Fedora, nor have I heard about 
LVM metadata before today.  All the damaged LVM header had for me was to 
hide my mostly intact filesystem from being fsck'd or mounted.

Further, you are full of care to have 11 copies of something you don't 
even need in, say, a laptop usage case, in case it breaks (because if it 
does break, you experience the truth of what I previously related about 
not being able to get at your filesystem).  This looks like a pointless 
and dangerous burden to place on someone who is getting nothing from 
having LVM there in the first place.  LVM on raid can make sense, in 
other common usage cases it is only a net risk.

-Andy