On Thu, Feb 15, 2018 at 5:18 PM, Stephen John Smoogen <smooge at gmail.com> wrote: > The only other thing I can think of is that the disk was already > formatted to GPT. In that case it has to be EFI. [I had a disk which > was GPT partitioned and removing that was quite a challenge as I had > done a 'dd if=/dev/zero of=/dev/sda bs=512 count=10' and it still kept > coming up as GPT. I believe I had to run a different disk command to > really clean it.] > That didn't get rid of it because GPT keeps a secondary copy of header info at the end of the drive. To really get rid of it use a tool that wipes GPT headers, or a full wipe of the drive. gdisk has eXpert mode that has an option (z) to wipe GPT headers. https://en.wikipedia.org/wiki/GUID_Partition_Table#/media/File:GUID_Partition_Table_Scheme.svg
