Western Digital has announced a new disk drive architecture that combines flash memory with high-density hard-disk drives plus a small CPU to manage everything.\nIf this sounds familiar, it is. Several years ago there was an effort by WD and other hard-disk drive (HDD) makers to build hybrid hard drives, with small flash drives acting as a cache for the hard disk, but those efforts failed, said Ravi Pendekanti, senior vice president of HDD product management and marketing at WD.\n\n\u201cThere was a huge pitfall in those [drives],\u201d he told me. The drives didn\u2019t know what kind of data they had, so they didn\u2019t know that hot data was frequently accessed and should be written on to the flash drive, while warm or cold that wasn\u2019t accessed as much should be written to the disk.\n\u201cNot everybody could actually figure out all the time as to where the data should go, or whether it's hot or warm or cold data, which is why it never took off,\u201d said Pendekanti. \u201cBut because of that, we're able to go forward with the lessons learned and how it's a different model than in the past.\u201d\nThe OptiNAND technology combines WD HDDs with iNAND flash memory chips and a special system on a chip (SoC) design from WD. The SoC will manage the storage of data, with live data going to the hard disk while metadata is stored on the iNAND flash. All data storage is managed by the SoC, along with the management of the drive, such as wear leveling of the flash storage.\nThere\u2019s more to this than a few new chips. WD is talking capacities of up to 50TB by the second half of the decade. It was able to add more capacity thanks to greater tracks per inch (TPI), which means higher storage density, coupled with the fact that metadata is written to the NAND rather than the disk like it is today. Hard drives can generate gigabytes of metadata, and retrieving and writing it means the hard disk, already the slowest component in the computer, is slowed further from performing its main functions.\n\u201cSo with these two in play, we are able to get more capacity. So instead of metadata taking up more space on your disk, and the fact that it goes in conjunction with adding more TPI that is giving rise to a higher areal density,\u201d he said.\nWD also improved the precision of HDD heads with a triple-stage actuator (TSA) technology, which enables better precision for a recording head on an HDD. That also enables higher areal density.\nThe new flash-enhanced drive architecture will be available across the company\u2019s entire line of drives and storage platforms and will serve as the foundation for future designs. For now, WD is sampling the drives to expected early adopters: hyperscalar and enterprise customers. \u201cIt is those two classes of customers who are going to use this for their typical drive use cases to run various applications,\u201d said Pendekanti.\nThe company will announce the first market-specific, purpose-built products later this year.