[CentOS] lvm snapshot

[Gordon Messmer]

On 12/02/2015 12:05 PM, Axel Glienke wrote:
> in journalctl i found:
> modprobe: FATAL: Module dm-snapshot not found
> ...
> Can't process LV root_snap: snapshot target support missing from kernel 

I installed a very simple CentOS 7 system with an LVM root FS. Created a 
snapshot and rebooted, no problem.  Updated dracut, then updated 
everything else and rebooted, no problem.

As far as I can tell, dracut normally includes the entire kernel module 
tree under kernel/drivers/md, which should provide the dm-snapshot 
module required to complete the boot sequence.

I can't determine what's causing the problem you see, but it doesn't 
appear to affect a standard installation.

Try:

dracut --force --debug > /var/tmp/dracut.txt 2>&1

Upload /var/tmp/dracut.txt to http://paste.fedoraproject.org/.  I'll see 
if I spot anything useful.