Reverting snapshots

In this recipe, we are going to create an internal snapshot of a running instance, introduce a change, then restore back to the original instance state using the snapshot.

Getting ready

For this recipe, we are going to need the following:

• A libvirt host with an existing QCOW2 image
• A running KVM instance, using the QCOW2 image
• The QEMU toolset

How to do it...

To revert the state of a KVM instance to an older state, from an existing snapshot, run the following:

1. Connect to the KVM instance and create a new file:

root@kvm:~# virsh console kvm1
Connected to domain kvm1
Escape character is ^]

root@debian:~# touch SNAPSHOT
root@debian:~#
root@kvm:~#

2. Create an internal snapshot of the virtual machine:

root@kvm:~# virsh snapshot-create kvm1
Domain snapshot 1492802417 created
root@kvm:~#

3. Get information about the snapshot:

root@kvm:~# virsh snapshot-info kvm1 --snapshotname 1492802417
Name: 1492802417
Domain: kvm1
Current: yes
State: running
Location: internal
Parent: 1492797458
Children...