The SATA International Organization, the industry consortium governing Serial ATA interfaces, yesterday released a finalized version of the SATA 3.0 specification, which features 6.0Gbps data transfers and a number of improved features while remaining completely backwards-compatible with existing drives, controllers, connectors, and cables. While current hard disk drives can't saturate SATA 2.0's 3Gbps data rate, SSDs can, and the new features are moderately compelling.
SATA launched in 2001, and has been through one prior speed bump, from 1.5Gbps to 3.0Gbps. The IDE-SATA transition and prior bump were both timed to give the industry about three years to adopt the new standard, making for a smooth transition, unlike, for instance, the 4GB file limit on FAT32 file systems, the 4GB memory limit on 32-bit x86 operating systems, or the 640k memory limit and extended/expanded memory misery of the 1980s. This new transition is significantly more urgent than the others, because SSDs are already saturating SATA 2.0.
The current new standard, when it ships in motherboards, RAID cards, and hard disks—probably early next year—will be urgently needed by SSDs, some of which have already resorted to double-ganging SATA channels, or even to PCIe links, to increase bandwidth. The benefits of SATA 3.0 will make themselves felt immediately in the SSD market.
SATA 3.0 also brings some other features to the table, including:
- An isochronous transfer mode (precisely analogous to the USB Isochronous mode) which uses NCQ to prioritize transfers for streaming applications like audio and video transmission
- More NCQ management features
- A pair of new connectors designed for 1.8" hard drives (which have been on the rise lately), and optical drives as thin as 7mm
The coming onslaught of new standards in motherboards, which will include USB 3.0, Firewire 3200, and SATA 3.0, might give rise to some interesting behavior in the market for motherboards. Standards transitions like this can sometimes make for shakeups in the motherboard market, like when VIA scored design wins on Intel by launching a Pentium 4 chipset with DDR memory in 2001, putting them ahead (temporarily at least) in the chipset market. As the transition to these new standards happens, the fine points of chipset comparisons may again hold interest, and the days when a $100 motherboard can power a high-end system may temporarily abate.
When the original standards were being drafted, SATA was slated to undergo at least two speed bumps, to 3.0 and 6.0Gbps, as needed. With the new 6Gbps standard finalized, engineers from SATA-IO member companies will be investigating the potential of a seamless transition to higher speeds, possibly 12Gbps, which was not explicitly planned in 2001. It's possible they'll succeed, but some interface engineers have expressed uncertainty, and even skepticism, that the transition will be managed. In this event, a modified SATA interface, or even a completely new interface, will be needed when a new standard is implemented, some time around 2013.