Creating new disk for VMM

To create a new disk for a virtual machine inside OpenBSD VMM, first login to the host machine:

$ ssh

Replace username and


$ vmctl create -s 20G newdisk.qcow2

Replace 20G with the disk size you need, and replace newdisk.qcow2. By convention, the disk name for the virtual machine will be the same as your username.

The hypervisor admin will then need to add your new disk to /etc/vm.conf:

vm "username" {
        owner username
        memory 2048M
        cdrom "/home/username/username.iso"
        disk /home/username/username.qcow2
        disk /home/username/newdisk.qcow2
        interface { 
                locked lladdr aa:bb:cc:dd:ee:ff
                switch "switch0"

The user should power off the virtual machine, either by logging in to the guest machine and running:

$ doas shutdown -p now

or logging into the host machine ( and running:

$ vmctl stop username

Or, the hypervisor admin will need to power off the virtual machine:

$ doas vmctl stop username

Next, the hypervisor admin needs to reload the configuration file;

$ doas vmctl reload

Now, log back in to the virtual machine guest. If you're on the hypervisor, type:

$ vmctl console username

Login, then verify that the disk has been detected:

$ dmesg | grep -E 'sd[0-9]'
sd0 at scsibus1 targ 0 lun 0: <VirtIO, Block Device, >
sd0: 20480MB, 512 bytes/sector, 41943040 sectors
sd1 at scsibus2 targ 0 lun 0: <VirtIO, Block Device, >
sd1: 20480MB, 512 bytes/sector, 41943040 sectors
root on sd0a (fd7ecb3de7e46e12.a) swap on sd0b dump on sd0b

You should see your old disk (sd0) and your new disk (sd1). Make sure to compare the disk size to ensure that you have identified the disks correctly.

The mount command can also show which disk is being actively used:

$ mount
/dev/sd0a on / type ffs (local)
/dev/sd0k on /home type ffs (local, nodev, nosuid)

You can then format the new disk.