Western Digital announces 22TB CMR and 26TB SMR hard drives: 10 platters plus ePMR
Western Digital today announces sampling of its new 22TB CMR and 26TB SMR hard drives at its What’s the next western digital event. As usual, hyperscale cloud customers will get the first dibs on these drives. The key takeaway from today’s presentation is that Western Digital does not yet feel the need to bring heat-assisted magnetic recording (HAMR) into the picture. In fact, WD doubles down on energy-assisted PMR (ePMR) technology and OptiNAND (first introduced in 20TB CMR drives). WD also continues to use the three-stage actuator it started shipping in the first half of 2020 in new drives. It goes without saying that the new high capacity discs are filled with helium (HelioSeal technology). The main change common to both drives is the move to a 10-stack design.
SMR drives get a further increase in capacity, thanks to WD’s new UltraSMR technology. This involves the adoption of a new advanced error correction algorithm to accompany the encoding of larger blocks. This improves the tracks per inch (TPI) metric, resulting in 2.6 TB per platter. The new Ultrastar DC HC670 uses ten platters to deliver 26TB of host-managed SMR storage to cloud service providers.
As part of the announcements, WD also provided additional details on the OptiNAND-enabled caching feature – ArmorCache. Last year’s announcement was pretty light on actual performance, but the 20TB OptiNAND drives have been on the market for a few quarters now.
UFS-based iNAND package helps OptiNAND-based hard drives improve IOPS up to 80% for large random writes at low queue depth (10%-20% improvement for small writes size) in use cases where write caching is disabled. Since non-OptiNAND hard drives can only cache whatever can be flushed to serial flash during emergency shutdown situations, the larger cache size offered by the iNAND device eases this limitation considerably. . As noted in the coverage of the OptiNAND announcement last year, use cases with write caching enabled benefit from the EPO data protection offered by the iNAND device. Enabling write caching often requires hosts to send cache flush commands to hard drives. These commands require the hard drive to stop accepting new commands until the dump is complete, which results in a loss of performance. ArmorCache makes these flush commands unnecessary, allowing the disk to be used at peak performance without the risk of data loss due to EPO.
The 22TB Ultrastar DC HC570 and 26TB Ultrastar DC HC670 are currently being sampled to hyperscalers. Volume shipping of the CMR player to the channel is planned for the next quarter. The Ultrastar HC HC670 is a host managed SMR player and will therefore only ship to select customers around the same time. Western Digital will offer variants of the CMR drive in its hard drive portfolio – 22TB WD Purple Pro for surveillance NVRs, WD Red Pro for NAS systems and WD Gold for SMBs and enterprises in the summer.
The updated capacity points – specifically, the increased SMR drive capacity – deliver clear TCO benefits to WD’s cloud customers. Basically, WD thinks they have enough confidence in their ePMR setup to ship hard drives larger than 30TB without having to go the HAMR route. From a tech standpoint, this will make the upcoming product roadmap/announcements from Seagate (HAMR rollout for publicly available drives) and Toshiba (need any tech beyond FC-MAMR) interesting to watch.