On a client site getting ready to add transactions logs to a new drive (for DAOS). I had always noticed the 8MB of unpartitioned space on Windows NTFS drives but never gave it much thought until the customer asked about it.

A few minutes on Google turned up this MS KB Article Q225822 where it states that up to 8MB will be reserved in case you ever convert the disk into a dynamic volume.

There you have it. I can now sleep soundly tonight.