Most SATA SSDs top out at 1TB, but a Chinese firm called Sage Microelectronics has developed a controller that enables drives with five times that capacity. The chip is already "shipping in volume" in a 2.5-incher that squeezes 2.5TB onto a single circuit board.
Unlike most SSD controllers, which are designed to work with individual flash memory chips, the Sage S68x family uses SD, MMC, and eMMC modules. Data is striped across up to 10 parallel channels, each of which can host four flash devices. A 10 x 4 x 128GB "array" is required to hit 5TB, and redundancy doesn't appear to be a part of the picture. The arrangement resembles a RAID 0 setup.
Source: Sage Microeleectronics
Flash cards require fewer traces than chips, according to Sage, making it easier to fit lots of storage within a limited form factor. The controller also lets drive makers mix and match JEDEC-compliant cards from different manufacturers. Each card is responsible for its own flash management.
The press release mentions a multi-core architecture that devotes one core to each pair of memory channels, plus one more to the Serial ATA interface. Surprisingly, though, it doesn't note the speed of that interface—or make any performance claims at all. That's probably because the SG68x is capped at SATA II speeds. The product page lists maximum sequential rates of just 260MB/s for reads and 225MB/s for writes. Random I/O rates aren't provided, but I'm not optimistic.
Sage says its controller is available for only $5 and that flash cards are price-competitive with NAND chips. The idea is that SSD makers can build ultra-high capacity drives for roughly the same per-gig cost as conventional SSDs.
For what it's worth, Sage's website also lists an S88x controller with a PCI Express interface. That chip appears to be limited to a single Gen2 lane, so it's not a speed demon, either.