The 20TB Red Pro comes from WD’s NAS line of hard drives, utilizing their unique OptiNAND technology. This technique marries mechanical and flash storage technologies to achieve higher capacity with a form of conventional magnetic recording (CMR) that's much faster than competing Shingled Magnetic Recording (SMR) drives. There is still a premium to be paid for this much space in a single device, and the performance is very predictable. The warranty is nothing to write home about, but if you need lots of storage for sequential transfers, the Red Pro will get the job done.
WD uses nine platters at 2.2TB each for the 20TB model, with extra capacity made possible by storing the necessary metadata on the onboard flash. WD’s vision is to use energy-assisted perpendicular recording (ePMR) to keep the benefits of CMR technology while offering unique benefits with OptiNAND. Many of the new features are only on the 22TB WD Gold so far, and while leveraging flash is a net benefit for WD, there is added complexity versus Seagate’s solution.
