[linux-lvm] F7 will not boot after running backup w/snapshot

Gerry Reno greno at verizon.net
Thu May 1 18:15:03 UTC 2008

Mikulas Patocka wrote:
> ... If you mount the origin device with missing snapshot, you destroy 
> the snapshot (even if you don't touch it). The snapshot can no longer 
> be repaired.
> So it is safer to not activate device in this case then destroy data.
Why? What value is the old snapshot at this point? You just had a system 
reboot in the middle of a snapshotted backup so all you need to do is 
get the system up, redo another snapshot and retake your backup. I'm not 
interested in the old snapshot.
> Imagine, for example, you have origin and snapshot, you reconfigure 
> disks in some weird way that the snapshot disk is inaccessible, you 
> boot, and the system automatically starts without the snapshot. And 
> you lose any data that you stored on that snapshot.
What is on the old snapshot at this point is probably indeterminate anyway.
> You can with dmsetup (but it has deadlocks). Maybe someone could write 
> non-deadlocky snapshot-managing tool that wouldn't depend on lvm vgs, 
> pvs and lvs.
> Mikulas
Have not used dmsetup. If it has deadlocks, I don't think I want to use it.


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