USB 3.0 vs. SATA 3.0

For years we have been stuck with slow data transfer speeds between storage devices, and now suddenly we have two new interface standards that promise to make slow data transfers a thing of the past. Enter USB 3.0 and SATA 3.0. We have tested both these interfaces and already have the results ready for you to decide which one is truly revolutionary and to be looked forward to. But first, let us look at what exactly these two new technologies are all about.

SuperSpeed USB or USB 3.0

After the agonizingly slow speeds of USB 1.1, USB 2.0 was a huge leap, as it increased the data transfer speeds by almost three times. USB 2.0 has a maximum data transfer speed of 480 Mb/s. Now, USB 3.0 has a maximum data transfer speed of 4.8 Gb/s, which is ten times that of USB 2.0. This bandwidth is even more than that offered by the SATA 2.0 3 Gb/s hard drives currently available. Naturally, the fastest hard drives available today can achieve its maximum potential when used as an external hard drive with USB 3.0 interface.

USB 3.0 connector

Being backward compatible, USB 3.0 connector plugs can be easily used with older USB ports on PCs and laptops and the speeds will automatically drop back to that of the older interface. The connector plug looks similar to the older USB connector plug, but a closer inspection reveals the presence of five new pins alongside the original four. These extra data lanes enable SuperSpeed performance.

It goes without saying that due to the addition of five extra lanes, the USB 3.0 cable is different and thicker than its older counterpart. USB 3.0 ports work with older cables as well, thus allowing you to plug in an old USB 2.0 hard drive. However, one problem that you may come across is, a USB 3.0 cable cannot be plugged into a USB 2.0 device, but that is understandable. USB 3.0 plugs can be easily differentiated from USB 2.0 plugs because manufacturers color code USB 3.0 plugs with blue plastic. Note that a USB 2.0 micro-USB plug can easily be plugged into a part of the USB 3.0 port on devices and it works in the USB 2.0 mode.

SATA 3.0 (SATA 6 Gb/s)

The SATA interface has been getting comparatively regular upgrades as it progressed from SATA 1.0 or 1.5 Gb/s to SATA 2.0 or 3 Gb/s and now to SATA 3.0 or 6 Gb/s.  After taking into account SATAs 10-bit encoding overhead, the effective bandwidth of this latest interface comes to 600 MB/s, which is twice that of its predecessor. It would seem that with SSDs threatening the very existence of mechanical hard drives, SATA 3.0 is the savior it has been looking for. But we'll know about that only after going through the test results.

SATA 3.0 cable

SATA 3.0 is backward compatible with older SATA interfaces, thus you can use SATA 3.0 devices with your existing motherboards with older SATA ports. The resultant connection will be equivalent to the older SATA interface. Likewise, older SATA devices can be used with SATA 3.0 ports, but the connection will only be equivalent to the older SATA interface. To get true SATA 3.0 connection, the device, port, as well as the cable have to be certified SATA 3.0.


Availability

USB 3.0 card

SATA 3.0 card

USB 3.0 and SATA 3.0 add-on cards are available to allow easy and inexpensive upgrade to the new interface. These cards work with a PCI Express slot. The other, but more expensive way is to upgrade to a new motherboard featuring these interfaces, though there are not many around at present.

 
Performance

We used the ASUS P7P55D Premium motherboard with the Marvel 9123 controller for SATA 3.0 and a Seagate Barracuda XT 2 TB hard drive featuring the new interface. For USB 3.0, we used the WD My Book 3.0, which came with a USB 3.0 interface card based on the NEC D720200F1 controller. You can check out the performance of SATA 3.0 here and that of USB 3.0 here. You can take a look at the real world performance test graph below to compare USB 3.0 and SATA 3.0. We have transferred 4 GB of assorted and 4 GB of sequential files to and fro to find the read and write times for each, and here are the results.

Clearly, SATA 3.0 is still ahead of USB 3.0 in terms of sheer file transfer speeds, but that is not the point in question. The fact remains that while SATA 3.0 is faster than USB 3.0, it is still not really much faster than its predecessor SATA 2.0. But when it comes to USB 3.0, it is certainly a lot faster than its predecessor USB 3.0, and while it is not really 10 times as fast, it is certainly more than thrice as fast.

Conclusion

While SATA 3.0 and USB 3.0 are both new standards in data storage device connectivity, we do have a winner. A winner for us is not necessarily the one which is faster, but the one which delivers more improvement over the previous standard and that which promises more. SATA 3.0 tests showed that the new interface shows improved burst speeds, but the real world performance remained more or less the same. This is attributed to the limitations of the spindle speed and the mechanical hard drive. SSDs should be able to overcome this speed limit better, but that remains too expensive an affair for most of us.

Therefore the runner-up of the two is SATA 3.0. USB 3.0 on the other hand was not found to be as fast as SATA 3.0, but that can be attributed to the hard drive inside the casing. Put in a faster hard drive and you will get faster data transfer speeds. USB 3.0 delivers more than three times faster performance than USB 2.0 and that is a massive improvement. In fact, that makes USB 3.0 the best thing that has happened to external storage drives after USB 2.0. Well, eSATA did look promising and the performance was very good, but it could not really replace USB 2.0 because of a host of issues such as lack of powered eSATA ports in motherboards.

For USB 3.0, this will not be a problem and users will get the same convenience of plug and play as USB 2.0. But now they can transfer larger files such as high definition videos to USB 3.0 drives without having to wait for too long. Now that makes USB 3.0 a winner. While this is our opinion, your opinion may vary. Please do let us know in the space below.