Bitlocker question

elvch01

Hi,

I am just configuring bitlocker on my Windows7 laptop and I have saved the key & recovery key to separate USB flash drives and have rebooted no problem. My only slight concern is that before I rebooted, I had 90Gb used of my 238Gb disk, but now I only have 6Gb free!!! Where has the other 140+Gb gone?

I have used TreeSize Free to verify that only 90Gb is actually in use, but when I do a DIR in a DOS window, I get

6,398,386,176 bytes free

I am hoping that this is just a temporary situation and will reslove instelf once bitlocker/windows has finished encrypting the disk, but would appreciate some reassurance please

elvch01

Google was my firend here

Why does it appear that most of the free space in my drive is used when BitLocker is converting the drive?

BitLocker cannot ignore free space when the drive is being encrypted because unallocated disk space commonly contains data remnants. However, it is not efficient to encrypt free space on a drive. To solve this problem, BitLocker first creates a large placeholder file that takes most of the available disk space and then writes cryptographic material to disk sectors that belong to the placeholder file. During this process, BitLocker leaves 6 GB of available space for short-term system needs. All other space, including the 6 GB of free space not occupied by the placeholder file, is encrypted. When encryption of the drive is paused or completed, the placeholder file is deleted and the amount of available free space reverts to normal. A placeholder file is used only on drives formatted by using the NTFS or exFAT file system.


from http://technet.microsoft.com/en-us/library/ee449438%28WS.10%29.aspx#BKMK_LongEncrypt