Hybrid drive is a logical or physical storage device that combines a fast storage medium such as NAND flash solid-state drive (SSD) with a hard disk drive (HDD), with the intent of adding some of the speed of flash storage to the cost-effective storage capacity of traditional HDDs.
The purpose of the SSD in a hybrid drive is to act as a cache for the data stored on the HDD, improving the overall performance by keeping copies of the most frequently used data on the faster SSD. These are sometimes called “SSHDs” — solid-state hybrid drives.
The drive automatically caches data in the solid-state storage for you, offering faster speeds for the files you use most.
There are two main configurations for implementing hybrid drives: dual-drive hybrid systems and solid-state hybrid drives.
In solid-state hybrid drives, SSD and HDD functionalities are built into a single piece of hardware, where data placement optimization is performed either entirely by the device (self-optimized mode), or through placement “hints” supplied by the operating system (host-hinted mode).
Hybrid drives work much in the same way as the current dual-technology configurations in many gaming and power-user PCs, as well as some ultraportable laptops.
Such systems have a small, discrete SSD to hold the operating system and frequently used data, augmented by a more capacious conventional hard drive for less frequently accessed data and large collections of documents and digital media.
Hybrid drive designs, in contrast, deliver both technologies within a single physical unit, and they employ software caching algorithms (rather than relying on the user’s brain) to decide which data belongs on the SSD portion and what goes on the drive’s platters.
Hybrid drives are a hybridization of traditional mechanical hard drive technology and more modern solid-state drive technology. The drives combine the large storage capacity of a traditional magnetic hard drive with the speed of a solid-state drive. The drives typically contain a 4-24GB solid-state storage area mated with a 500-1000GB magnetic storage area.
This configuration allows for frequently accessed data, boot information, and other data that benefits from rapid access to be stored in the solid-state portion of the drive while other data, such as media files and infrequently used programs, can be stored in the larger magnetic storage area.
Hybrid drives were introduced in 2007 when the price of large solid-state drives was still astronomical; as solid-state drive prices continue to fall hybrid drives will likely vanish as the compromise between storage size and speed will no longer influence consumer purchases.