Ultrastar 22TB HC570 drives
HC570 is the 10-disk CMB drive that also uses OptiNand just like the 20TB drive. As with the other Ultrastar drives, it is a 7200 RPM drive with similar transfer rates, available in SAS (WUH722222AL5201, WUH722222AL5204) and SATA interfaces ( WUH722222ALE6L1, WUH722222ALE6L4) with various encryption options.An MTBF of 2.5 million hours and a 5-year limited warranty are standard across the Ultrastar platform, and the 22TB is no exception.
Ultrastar 26TB HC670 Drives
The 26TB SMR drive (ULtraSMR, as WD calls it) is also a 10-platter drive, but can accommodate more data in an overlapping pattern, resulting in a 26TB capacity. Cloud service providers and large data centers would be the ideal customers for these 26TB drives.
Optinand - a game changer for WD
Starting with the 20TB drives, WD began using large NAND flash in the drives to store metadata, improve performance and increase data security. NAND is cheaper than DRAM and non-volatile, so the advantages of unit NAND are obvious. Some of the metadata traditionally stored on hard disks is stored on NAND, which means more space is available on spinning disks and the metadata can be read faster because NAND is faster than spinning disks. NAND can store up to 100MB of data if the drive unexpectedly loses power. This means that your drive will not lose data in the event of an emergency power failure, even if write cache is enabled.
OptiNAND will be used in all large-capacity WD drives given the benefits it offers.