Although SSDs are now essential on workstations, large capacity hard drives are still perfectly suited for intensive use on NAS storage systems. With OptiNAND technology, Western Digital’s 20TB Red Pro is still a fine number for network storage.
Designed for endurance, Western Digital’s range of Red Pro hard drives (3.5 inches) is a variation of the company’s so-called UltraStar models for NAS storage systems. The Red Pro WD201KFGX 20 TB (CMR) model we tested is equipped with a Sata III interface (6 Gb/s) and serves nine platters (2.2 TB with a surface area of 1,131 Gbit/sq²) with eighteen heads (three-level actuator) operating at a speed of 7200 rpm with 512 MB of internal cache memory to optimize the write and read phases. Note that WD also offers red hard drives (5200 rpm) at lower prices for small NAS configurations. Storage capacity is modest for the Red models (from 2 to 6 TB), while the Red Pro tops out at 22 TB.
The hardware architecture of the 20 TB Red Pro is a combination of everything WD offers to extend the life of its 24/7 hard drives, namely the use of ePMR (electrical Perpendicular Magnetic Recording) to reduce power consumption. operation and 1.6W in standby), reduced noise pollution and vibrations thanks to helium sealing of the case (HelioSeal) and 3D Active Balance technology, a tax on announced workload of 300 TB per year (data center models go up to 550 TB per year ), an estimated MTBF of 1 million hours, plus a five-year manufacturer’s warranty. In addition, WD has equipped its reader with NASware 3.0 technology integrated into the firmware, which improves the reliability and overall performance of the hard drive in a NAS, especially for the reconstruction of a volume in case of failure. Of course, to work well, all hard drives must be of the same type in the network storage subsystem.
OptiNAND technology leverages the storage capacity of WD hard drives by referring metadata retention to NAND flash. (Credit WD)
OptiNAND on a NAS hard drive
Of hybrid type, the Red Pro 20 TB benefits from OptiNAND technology with a NAND flash memory with a capacity of 64 GB (BICS3/3D TLC), which does not act as the buffer space of 512 MB. With OptiNAND and the algorithms built into the SoC-type controller, WD optimizes the use of its large-capacity hard drives without resorting to SMR and manages to reallocate some storage space to the data by pushing the metadata onto the NAND flash. As Ravi Pendekanti, senior vice president of HDD product management and marketing at WD, explained to us during a press briefing in September 2021, “there was a huge trap in these [disques durs hybrides d’ancienne génération]”. The drives didn’t know what type of data they contained, so they didn’t know that hot data was accessed frequently and needed to be written to flash, while hot or cold data that wasn’t accessed as much needed to be written to the hard drive.” Not everyone could always see where the data was going, or whether it was warm, hot, or cold data, which is why this system never took off. said Mr. Pendekanti.
“But thanks to this, we are able to move forward with the lessons learned and a different model than before.” OptiNAND memory with a UFS interface stores file-related metadata to optimize read and write head movements. This metadata, which was previously stored on the discs, also frees up space on the hard drives, as the higher the density of the hard drive, the more metadata it generates. In addition, OptiNAND is compatible with ArmorCache technology, for data security, which boosts performance and write cache protection. Poor block control as well as flash component wear smoothing is also driven by the algorithm associated with the controller.
With OptiNAND technology installed on the Red Pro 20 TB, WD optimizes the write and read phases by keeping movie metadata on 64 GB of NAND flash. (Credit WD).
For the test part, since it is not possible to measure the performance of this hard drive in a NAS bay in RAID mode – it would take several WD Red Pro 20 TB hard drives, we fell back on an individual test with a PC (Intel Core i9 10850K with an Asus Maximus XII Extreme motherboard with 64 GB DDR4). Just for information, since the use of this hard drive is more suitable for network storage, CrystalDiskMark shows an average speed of 269 MB/s for reading and 245 MB/s for writing (average of three measurements). Which is very satisfactory, although it is still far from the performance of SSDs still equipped with a SATA interface.
With its Red Pro 20 TB doped with OptiNAND, Western Digital offers a solid and resilient architecture if we respect the announced workload (300 TB per year). An interesting hard drive to equip small Sata NAS such as iXSystems, Qnap, Synology and of course Western Digital. It should be noted to conclude that the Red Pro 20 TB is marketed at a price of €465 excluding tax.