Thunderbolt interface strikes YOUR PC: What's the damage?
10Gbps, you say? Now for the reality check
I tested the drives and interfaces with the AS SSD benchmark as well as timing the transfer speeds of a 4GB image, a 17GB Blu Ray file and a 50GB folder of mixed file types and sizes.
So here's the theory...
Connecting the Elgato drive up to Thunderbolt delivered a bit of a shock in terms of performance. Certainly, it was much faster in the benchmarks than any of the other external interfaces, however, when it came to real life performance comparisons, it was slower when up against USB 3.0 – cue much scratching of head.
The answer to the surprisingly slow performance lies partly in the fact that the SanDisk Ultra uses a LSI SandForce controller – which has a real problem dealing with compressed data, such as media files – and the PCI-E to SATA interface that the Elgato uses. The ASMedia ASM1061 chip uses only a single x1 PCI-E lane and although it supports up to SATA 6Gb/s unfortunately, the SanDisk Ultra SSD relies on a SATA 3Gb/s interface.
Another thing to bear in mind is that although 10W of power can be delivered along the Thunderbolt cable, it also has its own power requirements, as both ends of the cable have active controller chips inside them each with their own draw on power before it reaches the external device.
I also got hold of Seagate’s GoFlex Desktop Thunderbolt adaptor which enabled testing of both 3Gb/s and 6Gb/s SSDs in the same device and doesn’t rely on power from the Thunderbolt cable as it is mains-powered. Although using the adapter showed the difference between using a 3Gb/s or a 6Gb/s drive quite nicely, the Thunderbolt performance still wasn’t that much faster than USB3.0.
Impressive performer: Seagate's GoFlex Desk Thunderbolt adapter
So after searching around for something that wouldn’t throttle the living daylights out of the bandwidth coming down the pipe from the PC, I acquired a WD MyBook VelociRaptor Duo. This is Western Digital’s latest external drive which packs two of the company's 1TB 10,000rpm VelociRaptor drives in an enclosure which can be set up in RAID 0 or RAID 1 array. Although the unit also uses an ASMedia ASM1061 controller (like the Elgato device), the VelociRaptor drives are running at the full 6Gb/s speed.
The resulting performance increase of just attaching the VR Duo drive was like night and day compared to the Elgato drive and showed just what speeds the Thunderbolt connection may be capable of. Getting another VR Duo and daisy chaining the two units together into a RAID 0 array sped the transfer speeds up, albeit only by a second for the 4GB image transfer but by a 90secs for the 50GB folder and by 14secs for the Blu-Ray image.
The Reg Verdict
So is the Thunderbolt interface a fast way of transferring data to an external drive? Well yes, but (and it’s a very big "but") to get the best out of if at the present time you have to choose the storage device(s) attached to the end of the cable very carefully. When it comes to data transfer, it suffers from bottlenecks in much the same was as other high speed interfaces. Even so, it proves itself as extremely capable of striking performance from external storage devices – those that are a match for its capabilities – with even an HDD topping the charts here.
Given the slow rollout of peripherals, Thunderbolt still has some way to go to prove itself, but its appearance on PC motherboards, at least, should see a ramping up of products that can match its performance potential. ®
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