A SSHD is the marriage of a platter hard drive and a SSD Controller linked to the same Nand flash used in a Solid State Drive. The drive electronics are a little more sophisticated than a regular platter drive deciding what is stored on the SSD portion of the drive using an algorithm that determines what is used the most often. Designed for desktop computers and DAS (Direct Attached Storage) situations the Seagate 4TB SSHD is the latest iteration of Hybrid drives from Seagate. The SSD qualities of the Seagate SSHD married to the capabilities of the platter portion of the drive let the drive have unique advantages over normal platter drives. Seagate's SSHD can achieve higher transfer rates and faster Bootups at a fraction of the cost of a SSD the same size.

SSD's remain on the expensive side for the amount of storage you get for the price you pay and it's rather a waste of SSD storage to say store large volumes of music or video on an SSD as the speed isn't going to do you a lot of good and frankly storing that amount of material on an SSD gets expensive fast. Last we checked you could snag a 240 ? 256GB SSD (good quality) in the neighborhood of $125 ? $140 with no frills models a little cheaper.