Additional partition being created when installing Windows 7

Question

I was formatting one my PCs to perform testing.

The first partition seems to be EFI or something that I shouldn't touch.

When creating a partition, Windows 7 automatically creates a 100MB blank partition before the partition that it will be installed on (which is then the 3rd partition). Why is this and what is this for?

With Windows XP, I can create a partition and IIRC, sometimes I may have a blank partition at the end which is small (approx. 8MB).

Can someone explain why Windows 7 creates a 100MB partition before the partition that it will be installed on? And why at other times there will be a tiny partition at the end? (NOTE I only care about the 100MB before my main partition).

Answer 1

The 100MB partition you're seeing is used by Windows 7 for:

• WinRE (Windows Recovery Environment)
• BitLocker.

You can prevent it from being created during setup by following these instructions at WinMatrix.

Note: they talk about a 200MB partition. Pre-RC1, Windows 7 used 200MB. But as of RC1, the Windows team reduced it to 100MB. Alternatively, you can pre-format and partition the drive before installing Windows 7, and the recovery information will be placed in your installation drive.

Answer 2

The 8MB is reserved for dynamic disk conversion

http://support.microsoft.com/default.aspx?scid=kb;en-us;225822

Not sure what the 100MB partition has to do with EFI, unless you're installing it with Bootcamp on a Mac, in which case there is a 100MB partition that is used for BIOS emulation I believe.

edit: With a Vanilla Win7 install I believe it puts the boot files there if it was previously unpartitioned. I can't find documentation from MS right now, but maybe someone else can.

Answer 3

If you don't like it, you can always partition manually using DISKPART or other utilities. You can bring up a command prompt to run DISKPART right in the Windows 7 setup environment by pressing Shift+F10.