Windows – When does BitLocker unlocks auto-unlockable disks

bitlockerencryptionwindows 8windows 8.1

Sorry for the tongue-twister in the title 🙂

I have 2 hard disks, one small and fast (system) and other big and slow (data), both fixed. I want to have both of them fully encrypted, and for that purpose I used Windows 8.1 and BitLocker.

I want the data disk being unlocked automatically, so I unlock it once manually and check the "automatically unlock" checkbox. After that, it unlocks automatically when booting. Great!

My question now is: when does this happens in the boot process? I've read Microsoft documentation saying that it happens "when you logon", but that is not very specific. Does it happen before booting Windows? Does it happen after being logged in?

The motivation behind this question is that I want to make some symbolic links from the small disk to the big one so I can save some space in rarely used folders, and the fact that the big disk might not be available until some unknown point in time could be a problem.

Best Answer

You mentioned the answer in your post already;

I've read Microsoft documentation saying that it happens "when you logon", but that is not very specific. Does it happen before booting Windows? Does it happen after being logged in?

This is actually very specific, assuming your computer is passworded, after you have entered your password and 'logged in', the drive will unlock.

Relevant information from the Microsoft Support document for Bitlocker:

Automatically unlock. Fixed data drives encrypted with BitLocker . Automatic unlocking for removable data drives can be selected after the drive is encrypted. To be able to automatically unlock fixed data drives, the drive that Windows is installed on must also be encrypted by BitLocker.

Source:
http://windows.microsoft.com/en-nz/windows7/learn-more-about-bitlocker-drive-encryption