I am trying to install Ubuntu on an external drive and I have tried several ways of partitioning the drive and none have them have allowed me to boot up. The one that is featured in one of the questions on this site:
When I install everything seems to be working and there is never an error message. However when I am choosing which drive to boot up from (holding down option while booting) it does not show up as an option.
I am running Macintosh 10.9 (Mavericks) and I have 8GB of RAM. The External HD that I am using is the Seagate Backup Plus Portable Drive: