Western Digital Introduces OptiNAND Tech Boost HDD Performance At 20TB And Beyond

Western Digital iNAND HDD
Western Digital announced plans to incorporate iNAND universal flash storage (UFS) embedded flash drives (EFDs) into its upcoming hard disk drives (HDDs) to enable increasingly larger capacities and improved performance, among other benefits. The name for this is OptiNAND, and it underpins Western Digital's storage roadmap up to around 50TB. That's a lot of storage space. Interestingly, this announcement comes the heels of a report that Western Digital and Noxia might combine forces to form a $20 billion NAND flash goliath.

Not to be confused with a cache buffer or volatile DRAM, this is something entirely different. Western Digital also swats away any notion of this being a hybrid HDD design, saying instead this is is a "smarter, faster, denser" solution that paves the way for much bigger capacities than what is on the market now, with non-volatile flash infused into the drive.

During its HDD Reimagine event, this was described as "a technology that enhances the drive. This is not meant to be a customer data buffering geared drive." The decision to go with iNAND for this purpose was made because it is an existing, small form factor (SFF) solution that is fast and non-volatile. That latter bit is key, because it means data is not lost in the event of a power outage.

"When we have non-volatile cache available, we have enough energy in the drive to take the data and write it to the NAND before any data is lost. When write-cache is disabled, we can leave it in DRAM knowing that if power is lost, we can make it safe," explains Bill Boyle, an engineer fellow of HDD research and development at Western Digital.

Combined with a triple-stage actuator (TSA) and HelioSeal technology, Western Digital says the first drives built around its new OptiNAND platform will cram an unprecedented 2.2TB per platter, with nine platters serving up 20TB of flash-enhanced storage space. The company has already begun shipping samples of these drives to select customers.

Adding this type of memory to HDDs means an overall more complex design. To deal with that, enhanced firmware algorithms will help juggle the expanded metadata that gets offloaded to the iNAND, which in turn enables more tracks per inch for increased areal densities.

Western Digital is also claiming gains in drive latency thanks to "proprietary optimizations" infused in the firmware. These optimizations are focused on reducing the number of adjacent track interference refreshes, to lessen the need for write cache flushes (in write cache-enabled mode).

It's an interesting approach, and Western Digital says it will employ its OptiNAND drive architecture across its portfolio of drives and storage platforms. Cloud and enterprise customers will undoubtedly be the first to benefit, though it sounds like this will be headed to the company's consumer offerings at some point too.