SATA 6Gb/s on Your New Motherboard?

There has been a lot of talk about the new "Serial ATA Revision 3.0 specification." New motherboards are now on the market with "SATA 6Gb/s" controllers, but what does all this mean to the enthusiast? Heck, what does "SATA 3" mean? We take a quick look at what "SATA Revision 3.0" is supposed to do for the world and what it will actually do for us on the desktop currently with RAID 0 and single disk configurations.

Introduction

Back about 10 years ago, we were introduced to Serial ATA Revision 1.0 Specification. And life was good! From an enthusiast standpoint, what we really got was skinny cables to replace those ugly and unmanageable ATA ribbon cables so many of us hated. Man, how those things were hard to route and make a clean looking rig? In the last decade we have seen SATA standards progress at a steady rate. Starting at 1.5Gb/s with Rev.1, to 3.0Gb/s with Rev. 2 and now 6Gb/s with "Serial ATA Revision 3.0 Specification." (1Gigabit per second = 100 Megabytes per second)

Without a doubt, the SATA interface has become the de facto standard for both mechanical and solid state data drives.

What's In a Name?

The Serial ATA International Organization AKA SATA-IO, is kind of picky about what SATA gets called. In fact we have already broken its rules in the paragraphs above more than once.

When referring to the specification, use "Serial ATA Revision 3.0 specification" for the first reference. For successive references, this can be shortened to "SATA Revision 3.0." Do not use "SATA 3.0." When referring to transfer rates, the technology can be correctly referred to as "SATA 6Gb/s."

Some of these naming conventions make SATA confusing to folks, which is totally understandable. We see "SATA 3" thrown around all the time meaning different things. Just do a search on "SATA 3" and see what all you come back with looking for a SATA Rev. 3.0 hard drive; not pretty. The SATA-IO should standardize on a naming convention that would reflect some information on the bus speeds. Till that is done, which is likely never since it actually makes sense, we will refer to SATA connects by the speed of the device as referenced above; SATA 6Gb/s. That way we are all sure what we are talking about. We do however have to give the SATA-IO credit for spelling out "6Gb/s" on the official badge / logo for the Revision 3 product. This will hopefully cut down on some of the confusion by more astute consumers.

Article Image

Serial ATA Revision 3.0 Specification AKA SATA 6Gb/s

Here are some key points to note about SATA 6Gb/s:

  • Up to 6Gb/s (600MB/s) data rates
  • SATA 6Gb/s Devices Backward Compatible with SATA 3Gb/s and 1.5Gb/s
  • Uses same cables at SATA 3Gb/s and SATA 1.5Gb/s
  • Real world transfer rates close to theoretical maximum

The overall gist of SATA 6Gb/s is pretty simple from a user perspective. The new controllers and bus are capable of delivering 2X the bandwidth of a "SATA II," rather SATA 3Gb/s. Same cables as the older specification, nearly the same power envelope. SATA 6Gb/s is a bit higher in terms of power consumption, but nothing to be concerned about in any way. This what SATA-IO has to say:

The end result is that moving from SATA 3Gb/s to SATA 6Gb/s data rates provides double the throughput without adding undue complexity or cost. SATA 6Gb/s also maintains its exceptional efficiency by not introducing additional overhead to the SATA protocol. This magnifies the value proposition of SATA 6Gb/s compared to SATA 3Gb/s, a factor that is sure to accelerate the migration to SATA 6Gb/s in the market place.

Very simple stuff, we get the ability to move 600MB of data per second across the SATA 6Gb/s bus. Of course you have to be able to fill the pipe. It seems that SATA 6Gb/s is very efficient as well. 600MB/s second sounds great, but what if half of that bandwidth is reserved for controller communication? This does not seem to be the case according to SATA-IO:

The realizable transfer rate across a 6Gb/s SATA link depends on the efficiency of the controller design on both the host and device sides of the interconnect. The SATA 6Gb/s interface transmits information at 600MB/s, however not all 600MB/s are realized as the user data payload because the protocol includes other data and handshaking communications between the host and device. In general, the SATA interface is very efficient. Realized transfer rates are typically very close to the theoretical maximum, which is one of the primary benefits of SATA technology for mass storage devices.