[linux-lvm] Cancelling snapshot merge

[Alexander Meshcheryakov]

Hello,

I had created snapshot of my /var logical volume a while ago and recently
It occured to me that I don't need saved state anymore and I would like to
reclaim disk space. But I have issued wrong lvconvert --merge command by
mistake instead of proper lvremove.

$ sudo lvconvert --merge VolGroup00/var_snap0
Can't merge over open origin volume
Merging of snapshot var_snap0 will start next activation.

I have figured out at this point that I made mistake. Luckily merge is
postponed as volume is used (mounted) now. But how do I prevent merge from
running upon next reboot? Here is what I have tried:

$ sudo lvremove VolGroup00/var_snap0
Can't remove merging snapshot logical volume "var_snap0"

$ sudo lvchange -an VolGroup00/var_snap0
Change of snapshot var_snap0 will also change its origin LogVol01. Proceed?
[y/n]: n
Logical volume var_snap0 not changed.


I even could not create snapshot of current state to roll back to it after
merge


$ sudo lvcreate --size 2G --snapshot -n var_snap1
/dev/mapper/VolGroup00-LogVol01

Snapshots of an origin that has a merging snapshot is not supported


Is there a way to cancel postponed snapshot merge?

[Zdenek Kabelac]

Post by Alexander Meshcheryakov
Hello,
I had created snapshot of my /var logical volume a while ago and recently It
occured to me that I don't need saved state anymore and I would like to
reclaim disk space. But I have issued wrong lvconvert --merge command by
mistake instead of proper lvremove.
$ sudo lvconvert --merge VolGroup00/var_snap0
Can't merge over open origin volume
Merging of snapshot var_snap0 will start next activation.
I have figured out at this point that I made mistake. Luckily merge is
postponed as volume is used (mounted) now. But how do I prevent merge from
$ sudo lvremove VolGroup00/var_snap0
Can't remove merging snapshot logical volume "var_snap0"
$ sudo lvchange -an VolGroup00/var_snap0
Change of snapshot var_snap0 will also change its origin LogVol01. Proceed?
[y/n]: n
Logical volume var_snap0 not changed.
I even could not create snapshot of current state to roll back to it after merge
$ sudo lvcreate --size 2G --snapshot -n var_snap1 /dev/mapper/VolGroup00-LogVol01
Snapshots of an origin that has a merging snapshot is not supported
Is there a way to cancel postponed snapshot merge?

vgcfgrestore - you could go via archive to the previous state of metadata.

There is no support for merge aborting - since it might have other 'side'
effects on metadata.

If you know what you are doing - vgcfgrestore is your rescue tool.

Zdenek