Unfortunately, while more secure and while offering a relatively seamless experience when sitting at your computer, the preboot authentication requirement for FileVault does pose a bit of a problem for those who access their systems remotely, such as through Screen Sharing (using Back To My Mac) or through SSH and other remote-access technologies. With CoreStorage, the OS configures a small hidden partition with a preboot welcome screen that looks like the standard OS X log-in window and contains user accounts that are authorized to unlock the volume and cause the system to load and automatically log in to the account specified on the preboot screen.
In OS X Lion, FileVault now uses Apple's new CoreStorage volume manager to encrypt the entire disk. OS X's encryption service, FileVault, originally stored users' home folder contents in encrypted disk images.
