Looks like Intel's next-generation Haswell platform will have some special sauce for hybrid hard drives. A new Seagate hybrid will be demoed at the Intel Developer Forum this week, and the press release says the drive makes use of a "Hybrid Information Feature" in the Serial ATA spec. That feature, which doesn't seem to be detailed on the SATA-IO site, is also supported by the version of Intel's Smart Response caching tech due in the second half of next year. It's unclear whether Smart Response Technology is required for the Seagate hybrid's caching scheme to work, though.
One thing is certain: Seagate isn't the only drive maker with a new hybrid in the oven. Western Digital has one of its own, and the thing measures just 5 mm thick. That's notably thinner than the 7-mm drives designed for ultrabooks and about half the thickness of the 9.5-mm models found in most notebooks. The press release is short on details, though it does reveal that the drive's solid-state cache uses MLC NAND. AnandTech claims the cache weighs in at 32GB, some four times the size of the solid-state component of contemporary hybrid drives.
Those current models come from Seagate, which has released two generations of Momentus XT hybrids already. The original came with 4GB of SLC NAND, while its successor bumped the cache up to 8GB. Both of those drives handle SSD caching internally, without the aid of special SATA commands or auxiliary software like Intel's Smart Response Technology. Seagate has stated previously that drive makers are the ones who should be in charge of hybrid caching, since they have the best information about how data is stored on the disk. That said, I can't help but wonder if we'll see some cooperation between hybrid drives and caching software like SRT, especially if there's a new SATA feature involved.