It is the 1TB fusion drive so it has the 128 GB of SSD not the 24 that is on some of the iMacs fusion drives. If I could do it over I probably would of just got 256 SSD. But how long does the drive last? It gets light use. The computer is in great working condition. And how much would it be to replace? If the HDD dies can I just connect a thunderbolt external drive to it?