Database Sizing for Orchestrator

I am using Orchestrator in a small environment where I will have less than 20 workflows.   I am using the virtual appliance and it's built in database, not an external database.  By default the hard drive size is 7GB.  What determines how big my hard drive size needs to be when i deploy it?  Is it the number of workflows, the number of plugins stored?  Is there a chart to help me look at all the things that might require more than 7GB, add them up and come up with a size needed for the virtual appliance hard disk?

Thanks!