Apex 23.04

This is a new app for managing virtual machines and QCOW2 disk images created by Virt-Manager for Qemu/KVM.

Apex provides a GUI for creating overlay files (“undo” disks) for the base disk image. When the overlay disk is attached to a VM, the VM sees the combined data from the overlay disk and the base image. However, changes made by the VM are written to the overlay disk instead of the base image. These changes can be committed (merged) to the base image, or discarded to reset the overlay disk.

This is similar to creating snapshots in VirtualBox. The base image acts as a “snapshot” after adding an overlay disk. The snapshot can be “restored” by discarding the changes in the overlay disk. Using overlay files is much more flexible than VirtualBox snapshots since multiple overlay files can be created for the same base image. Each of the overlay disks can be attached to the VM and booted when needed.

Internal Vs External Snapshots

Two types of snapshots can be created for QCOW2 files – internal and external. You may already be familiar with internal snapshots (also called internal checkpoints). The Virt-Manager GUI provides an option to create and manage these checkpoints. Internal checkpoints are easy to use but have the disadvantage that all data is stored in the same QCOW2 file. If you try to optimize or compress the QCOW2 file, it will delete the internal checkpoints to save space.

External snapshots on the other hand involve creating an overlay file (“undo” disk) that refers to the data in the parent QCOW2 image. When you attach this overlay disk to a VM, the VM will see the combined data from the overlay disk and parent disk, but any changes made by the VM will be written only to the overlay disk. If you are happy with the changes, you can merge the overlay disk with the parent, to create a single QCOW2 file. Or you can delete the overlay disk and create a new one to start again. You can create multiple overlay disks for the same parent disk. Each “undo” disk can be attached to the VM individually and used for making modifications.

Note

This app is meant to be used along with Virt-Manager. It is not meant to be a replacement. Virt-Manager’s UI is excellent and there’s no point in re-inventing the wheel. The only feature that Virt-Manager lacks is an option for managing overlay disks and external snapshots, which Apex aims to provide. For all other tasks, the Virt-Manager UI is invoked.

Purchase

A new license can be purchased from the below link.