Western Digital is saying the sampling of its new 22TB CMR and 26TB SMR laborious drives immediately at its What’s Subsequent Western Digital Occasion. As common, the hyperscale cloud prospects will get first dibs on these drives. The important thing takeaway from immediately’s presentation is that Western Digital would not but really feel the necessity to convey heat-assisted magnetic recording (HAMR) into the image. In reality, WD is doubling down on energy-assisted PMR (ePMR) know-how and OptiNAND (launched first within the 20TB CMR drives). WD can be persevering with to make use of the triple-stage actuator that it began transport within the first half of 2020 within the new drives. It goes with out saying that the brand new high-capacity drives are helium-filled (HelioSeal know-how). The principle change widespread to each drives is the shift to a 10-stack design.
The SMR drives are getting an added capability enhance, due to WD’s new UltraSMR know-how. This includes adoption of a brand new superior error correction algorithm to go together with encoding of bigger blocks. This enables enchancment within the tracks-per-inch (TPI) metric, leading to 2.6TB per platter. The brand new Ultrastar DC HC670 makes use of ten platters to offer 26TB of host-managed SMR storage for cloud service suppliers.
ArmorCache Expertise
As a part of the bulletins, WD additionally offered extra particulars on the caching characteristic enabled by OptiNAND – ArmorCache. Final yr’s announcement was fairly gentle when it comes to precise efficiency numbers, however the 20TB OptiNAND drives have been out out there for a number of quarters now.
The UFS-based iNAND bundle helps the OptiNAND-based HDDs ship upwards of 80% enchancment in IOPS for low-queue depth large-sized random writes (10% – 20% enchancment for small-sized writes) in use-cases the place the write cache is disabled. Since non-OptiNAND HDDs can solely cache no matter could be flushed out to the serial flash throughout emergency power-off conditions, the bigger cache dimension afforded by the iNAND system relaxes this limitation significantly. As mentioned within the OptiNAND announcement protection final yr, use-cases with write caching enabled profit from the EPO information safety afforded by the iNAND system. Enabling write caching usually requires hosts to ship out cache flush instructions to the HDDs. These instructions require the HDD to cease accepting new instructions till the completion of the flush, leading to lack of efficiency. The ArmorCache makes these flush instructions pointless, permitting the drive for use with full efficiency with no threat of knowledge loss resulting from EPO.
Concluding Remarks
The 22TB Ultrastar DC HC570 and 26TB Ultrastar DC HC670 are at the moment sampling to hyperscalers. Quantity cargo of the CMR drive to the channel is about for the subsequent quarter. The Ultrastar HC HC670 is a host-managed SMR drive, and can therefore ship solely to pick prospects across the identical timeframe. Western Digital shall be delivering variants of the CMR drive throughout its HDD portfolio – 22TB WD Purple Professional for surveillance NVRs, WD Crimson Professional for NAS techniques, and WD Gold for SMB and enterprise prospects in summer season.
The up to date capability factors – specifically, the soar within the SMR drive capability – delivers clear TCO advantages to WD’s cloud prospects. Crucially, WD believes it has sufficient belief in its ePMR setup to ship 30TB+ HDDs with out having to go the HAMR route. From a know-how perspective, this can make the upcoming roadmap / product bulletins from Seagate (HAMR deployment for publicly-available drives) and Toshiba (want for any know-how past FC-MAMR) attention-grabbing to look at.
