It was interesting to read this article recently which shows how strong current encryption technology is. The FBI and other organisations were apparently unable guess or crack the pre-boot passwords of criminal’s hard drives using a technique known as a dictionary attack. As it’s name suggests, a dictionary attack uses a combination of known words to attempt to guess the password. This is opposed to a brute force approach which would start from one series of characters and continue in a sequence to guess possible combinations.
It is worth remembering that if you are going to encrypt your hard drive that even the FBI can’t access your data if you forget the password. Also if the bootable part of your hard drive becomes unstable, it can be almost impossible to gain access to your data, even with the password. Make sure you test out your disaster recovery process on an encrypted drive, before you trust your crucial data to it. And also make backups somewhere that can be accessed quickly if required. Some large drives can take a day to decrypt even if they are fully functional.