Now I need a 2 TB ext HD for Time Machine backups of this 512 GB MBA. I used to use a 650 GB partition of a 750 GB HD for Time Machine with the 128 GB MBA & used the remaining 100 GB as a clone of the system. I'll set up 1.7 GB for Time Machine & 300 GB for a clone. I reformatted the 750 Gb ext drive into a single volume to use as a temp Time Machine backup until I can get an ext drive. An office supplier has WD 2 TB drives for $109 but I hate the extra WD partition you can't get rid of. So I'll possibly get a Seagate or Toshiba drive for about $20 more.