Backup and Restore KVM Vms

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Introduction

KVM stands for Kernel based Virtual Machine and according to Redhat, it is an open source virtualization technology built into Linux. Specifically, KVM lets you turn Linux into a hypervisor that allows a host machine to run multiple, isolated virtual environments called guests or virtual machines (VMs).

In today’s article, i will mainly cover the topic of KVM VMs backup.

Backup your KVM VM

First, Login as sudo and list all of your available KVM virtual machines.

Next, you need to shutdown the VM you want to backup.

Then run the following to verify that the above command worked well.

Backing up a KVM virtual machine mainly consists of two parts:

  • The domain definition:

The definition of the hardware of the VM including the network devices, configuration and virtual CPUs, disk and memory etc. You can view this through using the following command:

  • The data file

The source file path contains the path to our data file that we need to backup. It stores the hard drive of the VM. This is where the internal configuration is such as services, databases etc. In order to find the location of this file we can use the domain definition or we can use the following command which will give you the location of the hardrive.

Let’s suppose that the given location is:

In order to backup the domain definition, we run the following:

In order to backup the hard drive, we use the following

So, in the/opt/backup folder, we’ll find the domain definition and the hard drive of the VM.

To check the size of the hardrive : du -hs xxxx.qcow2

Restore your KVM VM

First, we’ll start by undefining the VM and deleting its hardrive so that it doesn’t exist anymore.

  • Undefine the VM:
  • Delete the harddrive
  • Restore the VM

Now, in order to restore the deleted VM, we first restore the hard drive:

Then, restore the domain definition

You can then checkout that the informations inside vm_name.xml are correct if you’re putting it on a different physical host. For example verify that the network interfaces exist on the new physical host etc.

Finall, run the following to verify that your VM have been correctly defined:

Then, start the VM:

Once your VM is running, SSH into it to verify that everything have been restored correctly.

References

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