The combination of NAND Flash memory and hard disk is increasingly in disuse due to the increase in storage capacity of SSDs, which is why the so-called SSHDs have fallen into oblivion in recent years. Western Digital looks like it wants to resurrect that concept with its newly introduced OptiNAND technology. Let's see what it consists of.
Through its HDD Reimagine event, Western Digital has presented new storage units, which it has dubbed OptiNAND and consists of the integration in a single device of hard drives and SSD units. This is not new, since that has already been done in the past with SSHD drives.
The advantage of these types of drives is that they combine the storage capacity of conventional hard drives with the transfer speed and seek time advantages of all NAND Flash-based memory. So in theory it brings together the best of both worlds in one device.
What is Western Digital's OptiNAND technology?
Future Western Digital hard drives will integrate 162-layer 3D NAND Flash memory into the circuitry that accompanies the hardware controller of their new hard drives. Specifically, they have integrated their UFS memory technology, so they are not NVMe chips. This is not a limitation or a bottleneck in performance since UFS memories are several times faster in transmission speed than a conventional hard disk.
And what is it that differentiates OptiNAND technology from a conventional SSDH? The fact that in OptiNAND the Flash memory does not store the complete data when copying the data, since it only stores the metadata that the hard disk uses internally to be able to perform certain operations more quickly and reliably. Hard drives usually come with a microcontroller with RAM memory that performs these operations. But being conventional RAM memory, this information is eliminated as soon as the hard disk has been turned off.
The fact that the hard disk has a large capacity of built-in NAND memory also means the increase in communication speed, as this allows you to send more data from the internal DRAM of the hard disk to the Flash memory built into these hard disks. This is achieved because the drive can use more rotational energy to send more data.
On which hard drives will it be implemented?
The first drives to use OptiNAND technology will be non-SMR hard drives with 20 TB capacity, which unfortunately we will not be able to buy, at least for a while, as Western Digital has stated that they will sell them first to a number of previously selected key customers.
WD's 20TB OptiNAND technology hard drives will consist of 9 platters and will continue to make use of energy-enhanced PMR or ePMR technology. From WD they affirm that OptiNAND technology is key to achieving the capacity of 2.2 TB per plate. Western Digital has plans to reach 50 TB of storage for its hard drives with OptiNAND technology.
