SATA 6Gb/s Doubling Speed, SATAp Adding Power
SATA-IO, or the Serial Advanced Technology International Organization isn’t taking the threat to their external storage supremacy lying down. They have two new specs in the works.
One is SATA 6Gb/s; which will, predictably, carry 6Gbytes per second, or about 568 MB/s after 8b/10b overhead. USB 3.0 is backwards compatible in the sense that the plugs will fit in the ports, but limits speed to the oldest of the cables or devices. SATA 6 (SATA 3 means 3Gb/s, there is no such thing as SATA 2 or II. Don’t blame SATA-IO: they saw this coming and tried to get people onboard with calling versions by their speed (like we do with FireWire and did with PATA). I was saying: SATA 6) will use identical cable and ports. Replacing cables isn’t that expensive relative to a new drive, but keeping track of them it a pain and the cost actually adds up quite a bit. This is even more significant when it comes to the ports built in to your PC enclosure, which will always be USB 2.0. A SATA port should behave according to the speed of the drive or controller (usually on the motherboard).
SATA 6 will hang on to its lower processor overhead and software requirement advantages. But it also hangs on to half duplex, while USB 3.0 goes full. It will be impossible to see which of these is fastest in practical terms until equipment is available to test. The point is: they should both have enough speed for most people’s (hard disk, not solid state disk, buyer’s) needs. Since USB can deliver power and obviate a separate power cable, and USB ports are just about everywhere, it comes out on top.
That is where power over SATA, or eSATAp, comes in. There aren’t many details on this yet, but there is an initiative to deliver at least enough power for a 2.5" HDD through SATA. Presumably, this will require a new connector. But it could be made backwards compatible with the existing one: compatible in the sense that it would fit, but not take advantage of the improvement. We examine this in detail, and bring FireWire into the mix, in the next article