LVM Snapshot

[kcrawford]

Hello,

I am attempting to create copy on write snapshot of my Windows Server 2008 R2 VM for testing purposes. I would like to be able to snapshot the VM at a point in time, make changes, delete the snapshot and be back to the time before taking the snapshot.

I have completed the following steps:

1. Created a snapshot of my vm disk image.

root@proxmox:~# lvcreate --size 5GB -s -n snap /dev/sky-vol/vm-101-disk-1
  Logical volume "snap" created

2. Added the disk image tag to the VM configuration.

root@proxmox:~# lvchange --addtag pve-vm-101 /dev/sky-vol/snap
  Logical volume "snap" changed

3. Edited the VM configuration file to use the snapshot as the ide0 device.

#ide0: container_storage:vm-101-disk-1,size=50G
ide0: container_storage:snap,size=50G

4. Attempted to start the VM, I receive the following error.

root@proxmox:~# qm start 101
unable to parse lvm volume name 'snap'

Can someone guide me as to what I am doing wrong?

*Also*, output from pveversion:

root@proxmox:~# pveversion -v
proxmox-ve-2.6.32: 3.2-126 (running kernel: 2.6.32-29-pve)
pve-manager: 3.2-4 (running version: 3.2-4/e24a91c1)
pve-kernel-2.6.32-20-pve: 2.6.32-100
pve-kernel-2.6.32-22-pve: 2.6.32-107
pve-kernel-2.6.32-29-pve: 2.6.32-126
pve-kernel-2.6.32-26-pve: 2.6.32-114
pve-kernel-2.6.32-23-pve: 2.6.32-109
lvm2: 2.02.98-pve4
clvm: 2.02.98-pve4
corosync-pve: 1.4.5-1
openais-pve: 1.1.4-3
libqb0: 0.11.1-2
redhat-cluster-pve: 3.2.0-2
resource-agents-pve: 3.9.2-4
fence-agents-pve: 4.0.5-1
pve-cluster: 3.0-12
qemu-server: 3.1-16
pve-firmware: 1.1-3
libpve-common-perl: 3.0-18
libpve-access-control: 3.0-11
libpve-storage-perl: 3.0-19
pve-libspice-server1: 0.12.4-3
vncterm: 1.1-6
vzctl: 4.0-1pve5
vzprocps: 2.0.11-2
vzquota: 3.1-2
pve-qemu-kvm: 1.7-8
ksm-control-daemon: 1.1-1
glusterfs-client: 3.4.2-1
root@proxmox:~#

 

[udo]

Hello,

I am attempting to create copy on write snapshot of my Windows Server 2008 R2 VM for testing purposes. I would like to be able to snapshot the VM at a point in time, make changes, delete the snapshot and be back to the time before taking the snapshot.

Hi,
there is an different naming with lvm-snapshots. If you delete the snapshot the "old" content was removed and only the uptodate LV was there!

I have completed the following steps:

1. Created a snapshot of my vm disk image.

root@proxmox:~# lvcreate --size 5GB -s -n snap /dev/sky-vol/vm-101-disk-1
  Logical volume "snap" created

And now you have all what you need! Any changes was written to /dev/sky-vol/vm-101-disk-1 and the old content was stored in /dev/sky-vol/snap
(this is the reason, why you can easy delete the snapshot).

If you want to revert you must do this (with switched off VM):

lvconvert --merge /dev/sky-vol/snap

Of course you should have an valid backup and test the scenario.

There are no changes in the VM-config!


Udo

 

[kcrawford]

This appears to have worked. I did power down the VM taking the snapshot and performing the merge(?) using the lvconvert command. I will test further to determine if this is needed.

Thank you for the quick reply.