Before starting the Opal servers it is very useful to take a snapshot. This enables you to roll-back the Opal servers to a pristine state, without needing to delete them and repeat the process above to re-import them.
To take a snapshot, first open VirtualBox and click on a server. Now click the button in the top right that says Snapshots , the camera icon (for VirtualBox 6, click on a server, click the three horizontal lines to open a menu and select 'Snapshots', then click the 'Take' button).
Remember you must repeat this for each Opal server
Snapshots can be named however you like. Also you can take as many as you like, to save different states of the Opal server.
For example, you could take Snapshot 1 straight after importing the Opal server, and then later Snapshot 2 after uploading some of your own simulated data.
