Accepted Solutions
Hi,
This should not be a problem. In fact I've used VMware Fusion for several years like this when I was living abroad.
Basically you delete the VM (choose keep) from the VM library, then move (or copy) the VM to your external disk and register it again (File -> Open)
On starting up the VM choose "Move" and not "Copy" as copy will make changes to your virtual hardware (new id's, if you run Windows that means re-activate), by choosing "Move" you prevent that from happening.
A couple of recommendations.
- Do not let your hard disk go to sleep (System Preferences -> Energy saver ), you want to prevent macOS from ejecting the disk when a VM is running.
- Depending on an external disk means that your setup is more fragile. Unplugging a disk by accident when a VM is running on it might corrupt the VM. I've had disconnects without much damage, but the risk of loosing the whole VM is real. IOW, make sure you get good and regular backups on another external disk. Plan for disaster, just in case the cat uses your disk as a sup board. 
- Use the fastest disk you can afford and use a connection that can cope with that speed. eg. if you buy an NVMe disk, make sure it isn't connecting via USB3 as you won't be able to use that awesome speed. A simple SSD would do in that case.
- Avoid slow laptop kind of drives (5400 rpm rotating disks don't cut it - at all, an absolute minimum would be 7200 rpm disks if you buy a spinning disk instead of a SSD/NVMe type of disk)
- Format the disk as HFS if you only store VMs on it (you don't need APFS disk wide snapshots for a VM, it does not help)
Oh almost forgot - Don't use Time Machine for making backups for VMs as that is not a reliable way to do so.
--
Wil
