How to Inspect, Convert, and Manage KVM VM Snapshots with qemu-img and virsh

First, verify the image format of the virtual machine by running

<code>qemu-img info /var/lib/libvirt/images/ehs-rac-01.qcow2</code>

, which shows the file format (qcow2), virtual size, and existing snapshots.

KVM uses raw format by default for best performance, but features such as compression and encryption require the qcow2 format; if the image is already qcow2, no conversion is needed.

To convert a raw image to qcow2, use:

<code>qemu-img convert -f raw -O qcow2 ehs-rac-01.img ehs-rac-01.qcow2</code>

Create a snapshot for the VM:

<code>virsh snapshot-create ehs-rac-01</code>

You can also assign an alias:

<code>virsh snapshot-create -as ehs-rac-01 ehs-rac-01-bak</code>

List existing snapshots:

<code>virsh snapshot-list ehs-rac-01</code>

Snapshot configuration files are stored under

/var/lib/libvirt/qemu/snapshot/ehs-rac-01/

.

Before reverting, shut down the VM:

<code>virsh destroy ehs-rac-01</code>

Revert to a specific snapshot by name:

<code>virsh snapshot-revert ehs-rac-01 ehs-rac-01-bak02</code>

Or revert by timestamp:

<code>virsh snapshot-revert ehs-rac-01 1500373324</code>

Delete a snapshot:

<code>virsh snapshot-delete ehs-rac-01 ehs-rac-01-bak</code>

After deletion, verify the remaining snapshots with

virsh snapshot-list ehs-rac-01

.