Preparing Your Hard Drive for BitLocker

In order for a computer encrypted with BitLocker to be able to boot, core operating system files must be stored in a separate, unencrypted volume. It doesn't need to occupy much space- only 1.5 Gb. But, if the PC was not configured and installed with BitLocker in mind, there is a very good chance that it is not properly partitioned for BitLocker.

I would suggest that Microsoft make the proper hard drive configuration the default for Windows Vista (and Windows Server 2008) installations, or at least present the option during installation. For example, ask the user if they intend to use BitLocker drive encryption and provide an opportunity to properly configure the drive right from the start rather than having to go back and fix it after the fact.

But, they haven't done that (...yet?). So, odds are very good that regardless of the size of your hard drive it is partitioned as one massive 'C:' drive, perhaps with some small partition that stores diagnostic tools provided by the hardware vendor. Thankfully, Microsoft developed a tool, the BitLocker Drive Preparation Tool, which automates the process of repartitioning the hard drive to get it ready for BitLocker encryption. If you want to use BitLocker but don't have the proper disk configuration, follow these instructions for using the BitLocker Drive Preparation Tool.