Using the current version of Virtual Box and the current version of Opal, we have found that on some platforms if you close down and power off the VM server in the usual way (by right clicking on the server and following the instructions, or by using the Machine menu) Opal halts incorrectly and prevents the VM from booting up correctly the next time. It is essential to take a snapshot of the pristine server when it is first imported (before you first start it up). Then you can always use that snapshot to start the VM correctly (with Opal working).

Before starting the Opal servers it is very useful to take a snapshot of each Opal server. 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:
Open VirtualBox and click on a server.
Click the further options button on the right side of the VM list, and select the further option Snapshots.

Take a snapshot of the server by clicking the leftmost camera icon:

Repeat for each Opal server.

You can customise the names of snapshots and 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.

Shutting down the Opal Servers

If no changes to Opal servers (e.g. for general users)

When you have finished your analysis, to shutdown the Opal server:

click the cross at the top right of the window. This will give you a list of options for how to shutdown the machine:
select Send the shutdown signal and check the box marked Restore current snapshot.

This will revert the Opal server to the state it was in when the snapshot was taken.

Any changes you have made since this point, such as uploading data or updating server-side packages will be lost.
If you wish to preserve changes made to the Opal training server follow Instructions if changes are made to Opal servers below.

If changes are made to Opal servers (e.g. for developers)

To shutdown the Opal server without losing any changes you have made to uploaded data or server-side DataSHIELD packages:

from the Opal training server command line log into the Opal using:

Username: root
password: puppet

type the shutdown signal into the command line:

$ sudo poweroff

Once the Opal training server has shutdown take a snapshot in order to preserve the changes made to the VM

Repeat for each Opal server

Snapshot the opal servers (windows)

Shutting down the Opal Servers

If no changes to Opal servers (e.g. for general users)

If changes are made to Opal servers (e.g. for developers)