High Quality Content by WIKIPEDIA articles! A hybrid drive, hybrid hard drive (HHD), or hybrid hard disk drive (H-HDD) is a type of large-buffer computer hard disk drive. It is different from standard hard drives in that it integrates a cache using non-volatile memory or even a small solid-state drive (SSD or SSH drive). Although the cache typically uses non-volatile flash memory, some drives use battery-backed volatile RAM (a hybrid RAM disk). The flash memory buffer can speed up repeated reads to the same location; a RAM buffer speeds both reads and writes, but must be written to backup storage before power is lost.