WD’s 22TB Red Pro is built on a standard 3.5in footprint but with a height of 26.1mm to accommodate the number of disks and actuators the drive uses. The drive has a spindle speed of 7,200rpm and there is an impressive 512MB of cache.
The drive uses 6th Gen WD HelioSeal Helium technology enabling the enclosure to hold ten 2.2TB aluminium discs along with twenty heads. The drive uses Energy-Assisted Perpendicular Magnetic Recording (ePMR) and triple-stage actuator (TSA) technologies which help combat the threat of magnetic inter-track interference (ITI) which can be a real problem with today's ever-increasing areal density disks.
The 22TB Red Pro uses OptiNAND technology. OptiNAND technology is a flash-enhanced drive technology developed by WD that integrates an iNAND UFS embedded flash drive (EFD), using 3D NAND, that sits on the hard drive PCB. It's the large chip on the far left of the PCB in the image above. The NAND isn't used to store user data as per the hybrid drives of the past, but instead is used to store the self-generated drive metadata instead of holding it on the disks themselves, freeing up more usable space.