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Windows 7, BitLocker and WinRE: Part 2

Allen Marsh


In a follow-on to my previous “Windows 7, BitLocker and Recovery” blog, I was wondering what would happen if you installed Windows 7 to an existing partition so that you ended up with a single partition instead of two, and then ran the BitLocker wizard. Or, if you made a 300MB active partition in the beginning of the disk and then told Windows setup to install to the free space.

In the “Hardware requirements for BitLocker Drive Encryption” section of the Windows 7 Help and Support, it states that the system partition must be at least 200MB. Then in the “Set up your hard disk for BitLocker Drive Encryption” section it states… “If your computer does not have a system partition, the BitLocker wizard will create one for you using 200 MB of available disk space.”

Yet the BitLocker wizard follows the Windows PE User’s Guide recommendation of 300 MB. Plus, it moves and reconfigures the Windows Recovery Environment from the boot drive to the newly created system drive.

Let’s summarize what you end up with the 3 scenarios:

Perform a clean install from the Windows 7 product DVD, enable BitLocker after installation.


Install from the Windows 7 product DVD to an existing single partition, enable BitLocker after installation.


Pre-create a 300MB active partition, have Windows setup install to the free space, enable BitLocker after installation.


These are significantly different outcomes. It really makes me think that it was a mistake not having Windows setup create a 300MB system partition and locate the Windows Recovery Environment there from the beginning. Or, maybe Windows setup shouldn’t even bother pre-creating the 100MB system partition. What is funny is that all SKU’s of Windows 7 create it, yet only Enterprise and Ultimate contain BitLocker. BitLocker is the one product feature that really requires two partitions. I could see if the Windows Recovery Environment was located in the 100MB partition by default, but it isn’t.

Having the 300MB active/system partition at the beginning or end of the drive could really be personal preference. If you ever wanted to have a recovery image stored locally on the machine, much like the OEM’s do, then having the 300MB at the beginning makes some sense. This allows you to then have a third partition at the end of the drive large enough to hold your image. I’m going to go with a 300MB system partition at the beginning, and then the BitLocker Wizard doesn’t have to shrink an existing partition later.

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