HDD’s big comeback

Traditional hard disk drives (HDDs) have their place as an integral part of datacentres and servers. The amount of data generated is growing rapidly so servers must keep up with a huge space demand.

The answer to large capacity requirements lays with HDDs that are characterised by a higher capacity and a lower total cost of ownership. Therefore, it is not hard to predict that in the next few years, we can expect to see larger HDDs entering the market over and above the 18TB and 20TB already announced.

Microwave-assisted magnetic recording (MAMR) and heat-assisted magnetic recording (HAMR) technologies are said to be the main ways to increase capacity. However, the introduction of the above technologies has been delayed, and the indirect energy-assist PMR (ePMR) method has been developed instead.

The ePMR method was discovered by Western Digital, and was developed during work related to MAMR. It is said the method makes use of a new physical phenomenon, although the manufacturer did not want to reveal exactly what that is.

The ePMR technology is already used by the highest capacity models in Western Digital’s offerings – WD Ultrastar DC HC550 18TB and WD Ultrastar DC HC650 20TB.

Of course, this is only the beginning of technology development and, over time, more and more capacious constructions using conventional magnetic recording (CMR) and shingled magnetic recording (SMR) will appear. Western Digital plans to release 20TB and 24TB media in 2021, 22TB and 26TB capacity in 2022, then 26TB and 30TB capacity in 2023.

After 2023, Western Digital plans to switch to MAMR technology, which will significantly increase the density of data storage and thus increase disk capacity.

While Western Digital is looking into MAMR and ePMR technology, another big player in hard drive manufacturing, Seagate, promises HAMR hard drives in 18TB and 20TB models will be available in 2020. The 18TB drive will use the same nine-platter design seen in the existing 16TB Exos drive and will use CMR. However, it’s another story for the 20TB drive.

Seagate is set to move from CMR to SMR for the 20TB drive. SMR designs utilise overlapping paths that are characterised by higher data density. The drive will also use HAMR, which temporarily heats the disk material and allows data to be written on much smaller regions. Seagate has been working on the HAMR technology for a long time, and the promise of higher areal densities with higher stability of data once written seems to be finally becoming a reality.

The future of HDD capacity development seems to be very promising. According to forecasts, in 2026 constructions with CMR recording are set to reach 50TB, and with SMR recording up to 80TB. Unfortunately, the introduction of new technologies will be associated with a cost increase.