Extend volume grayed out

I have a 3TB My Book and need to have a single partition using as much of the 3TB as possible.  The drive has two partitions, 2048 on the left and 746.49 on the right.  When I try to extend the left hand partition into unallocated right hand one, “extend partition” is grayed out.  I can format the right side but can not do anything with the left.

I have no problem with losing any data on the drive so I can reformat the entire drive if someone would explain how this is done.  When I try to do this, it only formats the left hand partition.

Thanks for any help.


It’s possible the drive was initialized as MBR as opposed to GPT. You may have to change the entire partition table in order to have a single 3TB partition.

For this process you will need to Write Zeros to the hard drive:




Thank you for the help.  It took 35 hours to write zeros to a 3TB drive but it worked and the drive is now operational.

Thanks again,


My pleasure.