In the agents Summary tab, the agent volumes are displayed.
To force a snapshot of an individual volume, the following must be done:
1) Select a volume that you don't want to snapshot, by clicking on the selection dial to the left of the volume letter.
2) Click on the settings icon, dropdown-box, on the far right of the highlighted volume.
3) Click on the "Set a schedule" heading.
4) Remove the volume from the schedule by deselecting the two schedule options : Mon - Fri, and Sat - Sun.
5) Click apply
The volume will now show as "Not protected"
Carry out the same steps for all volumes that you wish to exclude from the transfer/snapshot.
You can now select the volume you do want to snapshot, and force a snapshot on this volume.