KVM Guest Snapshots with Libvirt

Take a snapshot of your VM at any given point in time.
Have a mechanism to use the snapshot to revert your VM back to a previously working state.

Does KVM support snapshots?
What are KVM snapshots?
Where are KVM snapshots stored?
How do I take a snapshot of a VM in Linux?
How do I clone a KVM virtual machine?
How do I backup a KVM virtual machine?
What is Virsh?
How do I start VM with Virsh?
How do I delete a KVM virtual machine?
How does KVM snapshot work?
Where does KVM store VMS?
Where is QEMU stored?

Does KVM support snapshots?

Yes, KVM (Kernel Virtual Machine) does support both live and normal snapshots. The snapshot must base on qcow2 type disk. ... Never use qemu-img to modify images in use by a running virtual machine or any other process. Machine must be in shutdown state to use qemu-img command.

What are KVM snapshots?

Virtual machine snapshot is a copy of virtual machine's disk at the specific point of time. In other words we can say snapshot keeps or preserve the state and data of a virtual machine at given point of time.

Where are KVM snapshots stored?

So the default path would look to be /var/lib/libvirt/images for VMs that are using the default pool. That would be the same directory that temporary files related to -snapshot activity would reside as well.

How do I take a snapshot of a VM in Linux?

Create and Restore VM Snapshot in VirtualBox on Ubuntu Linux

Step:1 Start the VirtualBox.
Step:2 Select the virtual machine for snapshot and then click on 'Snapshots' option, in my case i am going to create a snapshot of CentOS 7 VM.
Step:1 Power off the Virtual Machine.
Step:2 Select the VM and Go to 'Snapshots' option and then click on “Restore Snapshot option”

How do I clone a KVM virtual machine?

How to Clone KVM Virtual Machines

Shutdown or Pause Virtual Machine to Clone. From the Virtual machine manager, simply select the vm in question and right click on it or simply click on the power to access the power menu to shutdown or pause a VM.
Clone the Virtual Machine. ...
Configure the KVM Clone.

How do I backup a KVM virtual machine?

How to Perform a Live Backup on your KVM Virtual Machines

Preparing Virtual Machines. First, you'll need to log in as the `virtkick user, you can do this by executing the following command as root: su - virtkick. ...
Create the backup. ...
Secure your backups. ...
Performing active blockcommit.

What is Virsh?

The virsh program is the main interface for managing virsh guest domains. The program can be used to create, pause, and shutdown domains. It can also be used to list current domains. Libvirt is a C toolkit to interact with the virtualization capabilities of recent versions of Linux (and other OSes).

How do I start VM with Virsh?

Virsh create a vm

If you would like to create a new virtual machine with virsh, the relevant command to use is `virt-install. This is crucial and can't miss on virsh commands cheatsheet arsenal. The example below will install a new operating system from CentOS 7 ISO Image.

How do I delete a KVM virtual machine?

To Delete a KVM Guest Using Virsh:

First, list all running KVM guests using “ virsh list ” command.
Next, you need to shut down a guest virtual machine using the “ virsh shutdown VM ” command.
Finally, delete a VM Guest with “ virsh undefine VM ” command.

How does KVM snapshot work?

The copy-on-write mechanism of qcow2 files allows each snapshot to take very small space. The space taken by a snapshot increases over time as the running image diverges from the snapshot. So as long as you are not rewriting a lot of data, your snapshots will take only a few MBs of storage.

Where does KVM store VMS?

In KVM , VM images are stored in /var/lib/libvirt/images directory by default. There might be the space limitation since /var filesystem lives under root-vg. In KVM virtualization, everyone would prefer to store VM images in central repository to migrate running VM from one hypervisor to another.

Where is QEMU stored?

In Fedora/RHEL, the guest configuration files are located under “/etc/libvirt/qemu” directory in the 'name' of the guest created in KVM.