With out a lot fanfare, Western Digital this week launched its first twin actuator exhausting drive, a 20TB drive that’s designed to supply SATA SSD-like sequential learn/write efficiency. The Ultrastar DC HS760 drive is supposed to extend IOPS-per-terabyte efficiency for hyperscale cloud datacenters and can compete towards Seagate’s twin actuator Exos 2X household of HDDs. In the meantime, Western Digital’s providing may even mark the most recent deployment of the corporate’s OptiNAND expertise.
The twin actuator Ultrastar DC HS760 HDD builds upon the corporate’s single actuator Ultrastar DC HC560 drive which makes use of 9 2.2TB ePMR (energy-assisted perpendicular magnetic recording) platters. However within the case of the HS760, WD provides a second actuator to the drive, primarily splitting it up into two quasi-independent drives with every half having area over 4.5 platters (9 surfaces). By doubling the variety of indepent actuators, Western Digital claims that the HS760 is ready to double sequential learn/write speeds and improve random learn/write efficiency by 1.7 instances versus single actuator drives.
Whereas the corporate but has to add a datasheet for its twin actuator HDD, we’re taking a look at sequential throughput charges of round 582 MB/s, which apparently sufficient is a tad quicker than SATA SSDs, which max out the SATA-III at round 550 MB/s. Although it is price noting that, as is typical for enterprise-focused exhausting drives, Western Digital is utilizing Serial Hooked up SCSI (SAS) right here, so it will not be attainable to hook the drive as much as a SATA host.
For the reason that two actuators inside Western Digital’s Ultrastar DC HS760 HDD work independently, the unit presents itself as two unbiased logical unit quantity (LUN) units, and each logical exhausting drives are independently addressable. Which means that datacenters must introduce sure software program tweaks (i.e., these will not be drop-in suitable with infrastructure designed for single actuator HDDs). However for the added complexity on the software program/configuration facet of issues, knowledge middle operators are being promised not solely the aforementioned larger efficiency ranges, but in addition a setup that’s 37% extra power environment friendly by way of IOPS-per-Watt than two 10TB units. In essence, hyperscalers are getting most of the advantages of getting two current-generation 10TB HDDs, however in a product that takes up the house of only a single drive.
The important thing benefit of Western Digital’s Ultrastar DC HS760 20TB over exhausting drives with one actuator of the identical capability is considerably elevated efficiency on an IOPS-per-TB foundation. Typical enterprise-grade 3.5-inch HDDs with capacities between 8TB and 16TB provide random efficiency of 6 – 10 IOPS per terabyte, which is sufficient to guarantee quality-of-service of datacenters. However at 20TB, random efficiency drops to lower than 5 IOPS per terabyte, which requires hyperscalers to introduce numerous mitigations to make sure that these drives meet their QoS necessities.
Such mitigations both embody implementing command queuing and latency-bounded I/O (LBIO) in firmware, utilization of drives of decrease capability, lowering usable capability per drive, and even including subtle caching strategies. All of those strategies both improve upfront prices and/or total-costs-of-ownership. Due to this fact, hyperscalers want drives that may bodily improve their IOPS-per-terabyte efficiency and twin actuator HDDs are a pure reply. As an added bonus, these exhausting drives additionally provide two instances larger sequential learn/write speeds than single-actuator HDDs.
As famous above, Western Digital shouldn’t be the one firm to supply twin actuator HDDs as Seagate has been doing this for years now. However Western Digital’s Ultrastar DC HS760 has a bonus over rivals that comes within the type of its OptiNAND expertise, which is an built-in iNAND UFS embedded flash drive (EFD) coupled with firmware tweaks. OptiNAND is supposed to extend capability, reliability, and efficiency of HDDs and whereas Western Digital but has to reveal efficiency numbers of its Ultrastar DC HS760 drives, it’s at the very least evident that its 20TB drive will provide extra capability than Seagate’s competing Exos 2X18 18TB drive.
In any other case, provided that the HS760 is aimed primarily at hyperscalers, Western Digital is treating the drive as a product for a restricted viewers. Though the drive is listed on the corporate’s web site, for instance, there isn’t any public pricing listed, and consumers must make a gross sales inquiry. So the precise unit pricing on the brand new drive goes to range some, relying on issues like order volumes and agreements between Western Digital and its shoppers.
Western Digital’s Ultrastar DC HS760 HDD might be lined with a five-year guarantee with every LUN rated for a 500 TB annual workload.