The retention period is the amount of time that you want to keep the database copies that are created from a database source. When the retention period ends, the expired database copies are automatically deleted from the Velocity Storage Server. You can continue to use any existing sandboxes that were created from a database copy after it is deleted. However, you cannot create a new sandbox from the deleted database copy.
If you do not set a retention period, you must manually delete the database copies from the Velocity Storage Server. Deleting database copies from the Velocity Storage Server lets you reclaim storage space.