[linux-lvm] Best practice: metadata backup

[Alasdair G Kergon]

On Sun, Aug 05, 2007 at 12:17:15AM -0400, Stuart D. Gathman wrote:
> LVM keeps backups of metadata in /etc/lvm (or some distro specific place).  
> This is not especially useful when the root filesystem itself is in LVM.  
> I have been making rsync backups of /etc/lvm to /boot (which is non-LVM
> since grub doesn't support LVM until 1.95).  Should I make /etc/lvm a
> symlink to /boot/lvm?
 
If you give /boot enough free space.

You can also change the location by setting the environment variable
LVM_SYSTEM_DIR.

> When grub supports LVM, and the entire disk is LVM (no partition table),
> how will backups be made?  

Just like any other file backups - tape, CD, internet: you choose!

> AIX treats the boot LV specially, and ensures
> that its PEs are contiguous at the beginning of the disk(s).  

Nothing is stopping a linux installer doing that today:
  --alloc contiguous and specify the extents.

But if grub supports LVM2 properly (add a trivial mapping layer from LV
extents to physical sectors, then populate it from the LVM2 metadata
across an agreed interface from a library maintained as part of the lvm2
package) it won't require anything like that of course - the hardest
problem I think is actually for it to identify the right disks to use.

Alasdair
-- 
agk at redhat.com