In order to run this backup procedure, the following requirements must be met:

     yum install reflink

Creating a snapshot of the virtual machine image is mandatory. Without it, the backup cannot be performed without stopping (or at least pausing) the virtual machine. Otherwise, copies would end up corrupted. As an alternative to OCFS2, you can store the virtual machine images in an external volume, in a directory that resides in an LVM logical volume. LVM supports volume-wide snapshots, that can be used instead of using the reflink command, but the procedure is not explained in this guide.