Western Digital 20TB WD Red Pro NAS Internal Hard Drive HDD – 7200 RPM, SATA 6 Gb/s, CMR, 512 MB Cache, 3.5″ – WD201KFGX

Designed specifically with medium or large scale business customers in mind, WD Red Pro drives are To be had for as much as 24-bay NAS systems. Engineered to take care of high-intensity workloads in 24×7 environments, WD Red Pro is ideal for archiving and sharing, in addition to RAID array rebuilding on extended operating systems such as ZFS or other file systems. These drives add value to your enterprise by enabling your employees to quickly share their files and back-up folders reliably on your NAS solution.

To be had in capacities ranging from 2 to 22TB(1) | (1) 1GB = 1 billion bytes and 1TB = 1 trillion bytes. Actual user capacity could also be less depending on operating environment.
For RAID-optimized NAS systems with unlimited selection of bays
Rated for 550TB/yr workload rate(2) | (2) Annualized Workload Rate = TB transferred x (8760 / recorded power-on hours). The maximum rated workload is specified for operating at typical temperature of 40C. Workload Rate will vary depending for your hardware and software components and configurations.
Designed to take care of the demands of high-intensity 24×7 multi-user NAS environments
Western Digital partners with quite a lot of NAS system vendors for extensive testing to verify compatibility with most NAS enclosures