Minivirt stores images and VMs in a database, which is just a bunch of folders and files. By default it's located at $XDG_STATE_HOME/minivirt/ (~/.local/state/minivirt/), but it can be changed by setting $MINIVIRT_DB_PATH.
An image is an immutable snapshot of a virtual machine. It typically consists of a qcow2 disk image and a configuration file. It's identified by an id which is calculated based on its files using SHA256. The image files reside in a folder named {db}/images/{id}.
An image may have tags, which are named references to the image. On disk they are implemented as symlinks to the image directory and are located at {db}/images/{tag}.
A VM is an instance of a virtual machine. Each VM has a unique name and its files reside in a directory like {db}/vms/{name}.
Typically a VM will be derived from an image, which is referenced in config.json under the "image" key. The VMs's qcow2 disk will have the image's disk as backing file.
At runtime, a VM will create several files:
run.jsoncontains runtime data like the SSH TCP port.ssh-configis a ssh configuration file for the VM.ssh-private-keyis the SSH identity key that can log into the VM.
The file {db}/remotes.json lists the remote repositories that are configured with the miv remote command.
When miv build needs to download a file, it will save a copy in {db}/cache, to speed up future builds. The cache is not cleaned up automatically, but it's always safe to delete any file from it.