What is SATA 6Gb/s?

R. Kayne

As of 2009, SATA 6Gb/s is the newest generation architecture for platter-based hard drives. The "6Gb/s" refers to the data transfer rate of 6 gigabits per second, twice the speed of the previous generation SATA. The Serial ATA International Organization (SATA-IO) that designs SATA standards has requested that this third-generation SATA be referred to as SATA 6Gb/s to avoid adding potential confusion to SATA nomenclature already bumbled by confusing second-generation names.

SATA cable connected to a drive.
SATA cable connected to a drive.

SATA technology changed the landscape of hard drive technology by switching from wide, inconvenient parallel ATA (PATA) data cables and connectors, to narrow serial cables and connectors. The switch to full duplex serial communication opened the door to faster speeds than parallel technology could handle, and also opened up the interior of computer cases allowing for greater air flow, vital to faster computer processor units (CPUs) and higher capacity disk drives.

A SATA cable.
A SATA cable.

Original SATA, also known as SATA 150 or SATA/150, had a maximum data transfer rate of 1.5 Gb/s or 150 Megabytes per second (MB/s). The fastest PATA drives could compete with original SATA, but PATA was maxing out its clunkier architecture while SATA was just getting started.

SATA 6Gb/s describes a newer generation of hard drive.
SATA 6Gb/s describes a newer generation of hard drive.

Second-generation SATA, often referred to as SATA II, doubled the speed to 3 Gb/s, or 300 MB/s. Due to the data transfer rate, SATA II was also called SATA 300, SATA/300 or SATA 3. You can already see the confusion with “SATA II” being synonymous with “SATA 3.”

Now add third-generation SATA and it’s clear why the SATA-IO does not want the newest iteration to be referred to as SATA 3, SATA III or even Third Generation SATA. Calling it by its data transfer rate, “SATA 6Gb/s” makes the specification immediately clear.

SATA 6Gb/s drives are expected to hit the market in the second quarter of 2009. According to SATA-IO, the technology is backward compatible with previous versions of SATA, using the same cables and connectors. Since SATA drives make up nearly 100% of drives in use today, upgrading to SATA 6Gb/s as easy as buying and installing a new drive.

SATA 6Gb/s is coming just in time to pair up nicely with USB 3.0, a newer USB standard. USB 3.0 supports a maximum theoretical speed of 600 MB/s, matching perfectly with the newest generation SATA. While USB 3.0 might not realize its maximum throughout in the real world, you can’t help but imagine all the time you’ll save with an external drive enclosure that supports USB 3.0, and two or more SATA 6Gb/s drives to speed through those disk-clone backups.

While some new technologies introduce as many new problems as they fix, no one has looked back since the introduction of SATA technology. Now with SATA 6Gb/s and USB 3.0 on the horizon, you can bet that everyone is looking forward.

SATA 6Gb/s matches the speed standard of USB 3.0, introduced in 2008.
SATA 6Gb/s matches the speed standard of USB 3.0, introduced in 2008.

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Discussion Comments


When a manufacturer says a drive will reach 6Gb/s that means 6 gigaBITS, not bytes! That translates to 600 megaBYTES per second. Hard (platter) drives cannot reach that speed on their own. Manufacturers are engaging in false advertising and while lately they have been putting the words "up to" on them, they are still misleading consumers!


I have a new 2TB seagate sata drive that is SATA 6 Gb/s. But my Intel Rapid Storage Technology service shows that the drive is running at 3 Gb/s. How can I configure it differently to run at 6 Gb/s?


I can only agree with the above, however here are my thoughts about solid state drives. It is a fact that these drives will be the fastest drives on the market. My concern is their lifespan. As we know, SSD cards are limited to their total number of writes to one cell. The same applies to the solid state drive. To my knowledge, there is a certain algorithm used to ensure, let's say a round robin is used to spread the write cycles. Whoever constantly updates the data will probably be very unhappy. The drive will run out of life fairly soon. Unless this is a reasonably long time, it's simply not ready.


@scienceguy34 >> Wrong, because usb has a total of 6GB/s for all devices whereas SATA will have 6GB/s for each device.


In fact speeds of SATA 6 are not even adequate for the current drive controllers from SandForce. They have just blown past the top speed of SATA 6 with their newest SF-2000 chip. Now everything is going to go through the 4 Lane PCI Express connector on the motherboard 4x PCIe here we come.


@mcsquare: Ditto on the SSD drives replacing the traditional platen hard drive. It’s already happening.

Personally, I think the fact that the new version of USB is essentially equal in bandwidth to SATA 6Gb/s will end up making SATA 6Gb/s obsolete. Instead of having SATA connections on the motherboard, there will just be more USB 3.0 sockets to which internal hard drives can be connected to—after all, USB 3.0 will have all of the capabilities that SATA 6Gb/s will have, possibly even more.

Consumers generally demand that their devices become more universal and more compatible with other technology, which necessitates a small number of connection protocols. If there are two equal protocols for attaching a device, one of them will dominate the other rather than both coexisting.


@AstroTurf >> True, traditional hard drives made out of platens, or metal disks, have inherit limitations to their speed. However, solid state disk drives have already pushed the current SATA speed limitations to the edge.

In the next decade, you will see the SSD (solid state disk) play a huge role in computing and will eventually replace the traditional platen hard drive. Solid state disks absolutely need a protocol like SATA 6Gb/s in order to reach their full potential.


This is another example of technology getting ahead of itself. The limits of transfer bandwidth are already limited by how fast the hard drive platens can spin. Even in a 10,000 rpm hard drive, the transfer rate will not have the potential to get anywhere near the current SATA limitations.

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