HDD+Fusion Drive computers
HDD+SSD Fusion Drive (2 drives)
— kind of "HDD + SSD" bundle (see the relevant paragraph), used exclusively in Apple computers and optimized for the proprietary "OS" macOS. However, it would be more correct to compare this option with the “HDD + Optane” combination (also described in its paragraph): for example, both drives are perceived by the system as single unit, and the Fusion Drive module is also used as high-speed cache for the hard drive. However, there are also significant differences. Firstly, Fusion Drive has significant volumes and is used not only as service buffer, but also as part of full-fledged drive — for permanent data storage. Secondly, the total volume of the entire bundle approximately corresponds to the sum of the volumes of both drives (minus couple of "service" gigabytes).In general, this type of drive is expensive, but the efficiency and convenience are well worth the price.