All you ever needed to know about Time Machine backups :
Turning Snapshots ON or OFF manually:
This requires using the Terminal app, in your Applications/Utilities folder.


Copy the appropriate command after the prompt, then press Return:

1. To turn Snapshots ON: sudo tmutil enablelocal
2. To turn Snapshots OFF: sudo tmutil disablelocal
3. To make a Snapshot: tmutil snapshot
 They're not real backups.  It's just a passtime for OS X and your startup drive.  Why bother?