Apple provides several layers of security when it comes to your Lion installation. 1. There is a hidden partition on your hard drive if things go wrong (press Command-R during startup to access it). 2. Internet Recovery: This feature downloads Lion from an Apple server if the hard drive fails and there is no previous Lion installation available. 3. Create your own Recovery USB drive with Apple’s Lion Recovery Disk Assistant. 4. Restore from Time Machine Backup (if you have one). You can also create your own Lion restore solution, which doesn’t need Internet access.