Western Digital spends 26 TB on its SMR hard drives

Last Monday, at a press conference in San Francisco, Western Digital unveiled a series of 7,200 rpm hard drives for data centers (enterprises and hyperscalers), including an UltraSMR mechanical model with a capacity of 26 TB (Ultrastar DC HC670). “Our intention in adopting this development strategy was not only to meet the capacity demands of the cloud giants, but also to provide a roadmap that would also support the economic evolution of their data centers for decades to come. said Ashley Gorakhpurwalla, vice president and head of HDD Business at Western Digital. “With ePMR, OptiNAND and now UltraSMR as the foundation of Western Digital’s hard drive roadmap, our cloud customers can continue to rapidly scale their business by taking advantage of our innovations to lower their total cost.” of storage. »

Western Digital therefore markets an SMR (Shingled Magnetic Recording) hard drive with a capacity of 26 TB (Ultrastar DC HC670) and a 22 TB CMR (Conventional Magnetic Recording) model (Ultrastar DC HC570 and its Red Pro, Purple Pro and Gold Pro) Designed for servers and storage arrays (NAS and others), these drives are helium sealed (HelioSeal) to reduce platter vibration and improve reliability, and leverage ePMR (electrical Perpendicular Magnetic Recording) to reduce energy consumption and OptiNAND to increase usable capacity. Remember that this flash memory equipped with a UFS interface stores file-related metadata to optimize the movement of read and write heads. This metadata, which were previously kept on the platters, also frees up space on the hard drives.Another advantage of OptiNAND is the write cache.A bap data security feature ized ArmorCache improves the performance and write protection of the cache.

The 26 TB are obtained in SMR mode and the 22 TB in CMR. (Credit Western Digital)

10 boards on the last DD

All these models accommodate 10 platters – compared to 9 on the previous 20 TB CMR and 22 TB SMR models – with a density of 2.2 to 2.6 TB per disk. SMR has about a 20% advantage over CMR since it leaves less space between tracks on platters. And, the UltraSMR crams more write tracks onto a platter by overlapping them in blocks, but without overlapping the narrower read tracks. On the 26 TB, WD has also adopted an error correction algorithm improving the encoding of larger blocks. If the rotational speed is the same on the SMR and CMR models (7,200 rpm), the reading and writing performances are however different. On SMRs, write speeds are slower, as entire blocks must be copied, modified with new data, and then written back to the platters. The start-up Kalista.io is tackling precisely this performance problem, especially when used in a RAID configuration. If the hard disk controller manages the read/write process of SMRs in Drive-managed mode, an additional software layer like that of Kalista reduces read latency and speeds up the write process on SMRs in Host-Managed mode. Its Phalanx software restructures write operations and transforms SMR areas into sequential sequence to improve throughput.

The Ultrastar DC HC570 (22TB) and Ultrastar DC HC670 (26TB) are currently being tested at hyperscaler cloud storage vendors. Delivery is expected next quarter, in small quantities for the 26TB model. 22TB variants Purple Pro for CCTV, Red Pro for NAS and Gold for SMBs and enterprises are scheduled for summer. Note that WD’s main competitor, Seagate, still caps at 22 TB in SMR mode and 20 TB in CMR, but announcements are expected in the coming weeks.

A 15.36 TB SSD for data centers

In addition, Western Digital is expanding its range of NVMe SSDs with a PCIe 4.0 enterprise model with a capacity of 15.36 TB, the SN650 in 2.5-inch and E1.L formats. It uses BiCS 5 technology (112 layers) in TLC (3 bits/cell). The supplier has been stingy with the features and performance of this SSD, with deliveries expected in the second half of this year. Another SSD announced on Monday, the SN740, a more modest PCIe 4.0 NVMe model (1 or 2 TB) aimed at laptop vendors with sequential read speeds of up to 5,150 MB / s. It inaugurates an M.2 form factor in 2230, 2242 and possibly 2280 variants, also using BiCS 5 technology in TLC. Finally, for the general public, the Black SN850X NVMe (PCIe 4.0) and the Black P40 Game Drive (external model with a USB 3.2 link) meet the needs of gamers. Available this summer, the SN850X is based on BiCS 5 3D NAND with capacities of 1, 2 and 4 TB, while the P40 Game Drive is offered in 500 GB, 1 and 2 TB.

To meet business needs, flash capabilities are increasing in data centers with the latest standard form factor SSDs. (Credit WD)