How to format a seagate "one touch" external drive with HFS+ on a Mac Pro?

Select the drive by its immutable manufacturer-given name in disk Utility.

If not shown, use the little drop-down menu to select View: show all devices.

choose GUID partition Map and HFS+ Extended (journaled).

give it a name.

wait a minute and Disk Utility will mount if for you.

now Disk Utility owns it, and the built-in drivers can always access it even to do a restore or in recovery mode.