In relation to your questions, the answers are inline:
- How does a workflow select the next snapshot to be copied?
- Answer - usually the Backup Copy workflow will select the oldest Snapshot to process for the Backup Copy.
- Does allow maximum jobs have a limit of how many jobs run at one time?
- Answer - I believe the limit for simulataneous Backup Copy is restricted to 7
However in SP9, we have introduce "you can run multiple backup copy operations from the storage policy level in parallel"
- The benefit of having parallel backup copy operations at storage level is that you can run backup copies of snapshot jobs of subclients that have new snapshots, if old snapshots are already copied with the previous backup copy workflow, while other subclients are still running the backup copy operations of the previous backup copy workflow.
For more details on the functionality of Backup Copy, please refer to the following Documentation - http://documentation.commvault.com/commvault/v11/article?p=11739.htm
At the moment, if you do have a backlog of Snapshot on the Storage, I would recommend to run additional Backup Copy workflow, so you don't fall behind
Hopefully that helps