Western Digital has delivered 20-TB and 18-TB hard drives announced. The 20TB Ultrastar DC HC650 SMR and the 18TB Ultrastar DC HC550 CMR were sampled by partners such as enterprise OEMs and hyperscale cloud providers, including Dropbox. Both hard drives have in common an Energy Assisted Magnetic Recording (EAMR), which according to Western Digital is a sub-group of Microwave Assisted Magnetic Recording (MAMR) – the manufacturer has not yet given details.
The Helium-filled Ultrastar DC HC650 has 20 TB in 3.5-inch format and uses Shingled Magnetic Recording (SMR). This type of recording with overlapping tracks enables a higher capacity for each of the nine platters in the HDD, but reduces the writing speed. The Ultrastar DC HC550, also provided with helium, has a capacity of 18 TB and relies on Conventional Magnetic Recording (CMR).
Due to their size, manufacturers can use the Ultrastar DC HC650 and the Ultrastar DC HC550, according to Western Digital, to reduce costs a little bit during operation, since fewer racks can be used for the same storage space. This should reduce power consumption and cooling costs. However, hard drives with a very high capacity are only of interest to certain customers because the access time remains the same.
The 20TB Ultrastar DC HC650 SMR and the 18TB Ultrastar DC HC550 CMR are scheduled to appear in regular stores in the first half of 2020, when Western Digital expects series delivery of the two EAMR hard drives.