A lot of attention has been paid to high-speed I/O interfaces for computing systems over the last five years. Flash-based storage media capable of multi-Gbps throughput have become very affordable. Display resolutions have also seen a rapid rate of increase. The necessity to support multiple such devices in both consumer and professional computing solutions have exposed the limitations of the traditional external I/O interfaces. While USB 3.x has become successful as an interface for high-speed peripherals, it does not handle display output. Intel has been attempting to solve this problem with Thunderbolt Technology since 2011. Unfortunately, the uptake outside the Apple ecosystem for the first two versions has been minimal at best. Thunderbolt 3, however, promises to be a game-changer. Systems and motherboards with Thunderbolt 3 support started shipping in late 2015. The first Thunderbolt 3 peripheral to appear in the market was the Akitio Thunder3 Duo Pro, a hardware RAID solution with two drive slots. This review looks at the various features of Thunderbolt 3 and what the Akitio Thunder3 Duo Pro brings to the table.

Introduction and Setup Impressions

Direct Attached Storage (DAS) units have been the go-to devices for consumers looking to store and have fast access to large amounts of data. The advent of high-speed interfaces such as USB 3.x and Thunderbolt have enabled a new generation of DAS units that allow the host system to access the member disks without any bottlenecks. We have looked at a few DAS solutions with Thunderbolt 2 before. Today, we are reviewing the first storage solution with Thunderbolt 3, the Akitio Thunder3 Duo Pro. The unit has daisy chaining support (i.e, two Thunderbolt 3 ports), a USB 3.1 Gen 1 device interface and a full-sized DisplayPort 1.2 output that is driven by the DisplayPort lanes in the Thunderbolt 3 link.

The Akitio Thunder3 Duo Pro is meant for desktop use and needs an external 90W power adapter (12V @ 7.5A). The chassis design also allows for stacking, if needed. In addition to the main unit and the power adapter / cord, the package also includes a Thunderbolt 3 cable (capable of 40Gbps data transfer) and a USB 3.1 Gen 1 Type-B male to Type-A cable. A cable-tie, quick setup guide, warranty terms and a reminder to update to the latest drivers / firmware for the host PC are also included. The detailed specifications of the unit are provided in the table below.

Akitio Thunder3 Duo Pro Specifications
Internal Storage Media 2x 2.5" / 3.5" Drives
Interface 2x Thunderbolt 3 + 1x USB 3.1 Gen 1
RAID Modes RAID 0 / RAID 1 / JBOD / SPAN - Hardware Selection Dial
Cooling Aluminium Chassis + Fan
Power Supply 100-240V AC Switching Adapter (12V @ 7.5A DC)
Dimensions 23.8cm x 14.3cm x 9.4cm
Product Page Akitio Thunder3 Duo Pro
Price $378

The gallery below takes us around the aluminum chassis. Important aspects to note include indicator LEDs for the two drives in the front panel and the perforations (which have a filter on the inside) that allow air to be pulled into the unit, over the drives and out through the fan. The rear panel is flanked on either side by screws that can be removed without the need for any tools. Loosening them allows for the external chassis to slide out.
The rear panel has a fan and a switch to control it (can be turned off for SSDs). Two Thunderbolt 3 ports, a full-sized DisplayPort 1.2 output, a power input jack and a USB 3.1 Gen 1 Type-B female port make up the lower part of the rear panel. A Kensington lock slot and the RAID-level selection indicator form the rest of the features.

The RAID-level selection indicator is covered by a plastic film from the inside that makes it impossible to accidentally change the RAID level without opening up the unit.  The gallery below shows the internal components of the Akitio Thunder3 Duo Pro.

On the board side of things, we have the Intel Alpine Ridge Thunderbolt 3 controller in its dual-port form (). The ASMedia ASM1153E fulfills the SATA to USB bridge functionality for the USB 3.1 Gen 1 device port. On the SATA backplane, we have the ASMedia ASM1062R SATA RAID controller that bridges 2x SATA III ports to two lanes of PCIe 2.0. The backplane also has an ASMedia ASM1456 signal switch to mux / demux SATA signals.

The setup process is simple, since the Thunder3 Duo Pro involves hardware RAID. Installing the SSDs or HDDs is a simple tool-less affair. Removal is a bit complicated, since the drives have to be gently tugged out from the SATA connector. A flat screwdriver can be used to set the desired RAID level (RAID0, RAID1, JBOD or SPAN). In case of a live switch of RAID level (i.e, change while the unit is powered on, it is necessary to press the 'Set RAID' button that is visible in the rear panel once the chassis has been slid off. Otherwise, one just needs to set the pointer to the desired RAID level and boot up the unit.

In the rest of the review, we first take a look at Thunderbolt 3 in detail, followed by a description of how our testbed was built and details of our evaluation methodology for the unit. We then talk about the various standard performance benchmarks. Following that, some special Thunderbolt-only aspects such as daisy chaining and its performance implications are discussed.

The Nuts and Bolts of Thunderbolt 3


View All Comments

  • name99 - Thursday, April 14, 2016 - link

    I don't understand this obsession with daisy-chaining. Daisy-chaining is a LOUSY technology. It's been a lousy technology in every damn form it's ever shipped, whether SCSI, ADB, firewire, or thunderbolt. One of the few things USB actually got right from the start was to make it clear on day one that their expansion solution was hubs, not daisy-chaining.

    Why does it suck?
    - It substantially reduces your power-on-off flexibility. This may not matter in a testing lab, but in the real world there are constant reasons why you might want to power a device off. With a hub this is a simple issue; with a daisy-chain it requires considering the implications of everything that is connected, and generally unmounting a bunch of devices then changing the topology.

    - right now when it's all skittles and roses, every thunderbolt device comes with two ports. But as soon as this goes mainstream, the usual attempts at cost-cutting will have one device after another shipping with only one port. And then what happens to your chaining?

    Because USB got this right on day one, USB hubs have always been cheap as dirt. Everybody owns one, and devices that need to present the illusion of daisy-chaining (like keyboards with two USB ports, one for the mouse to connect to; or displays with USB connectors) just stick in a cheap USB hub chip. Because Firewire (and the other specs I mentioned) did NOT get this right, FW hubs never became cheap. Even the FW400 hubs were expensive, and I don't think decent FW800 hubs were EVER produced (when I was looking for them, the best I could find was a pathetic two port hub).

    Instead of cheering how great Thunderbolt daisy-chaining is, you should be considering the reality that, because Intel has insisted on doing things this way (in spite of THIRTY YEARS of evidence that it is a stupid idea) they are likely going to snatch defeat from the jaws of victory. All those thunderbolt-enabled USB C ports will ACTUALLY land up connected to pure USB3.1 hubs, which will in turn, once again, mean that USB3.1 is the only really viable mass market for storage, and these super-high-end storage solutions (and external GPUs, etc) will continue to remain irrelevant to the mass market.
    Nice going Intel --- turns out instruction sets are not the only things you're incapable of handling competently.
  • Klug4Pres - Friday, April 15, 2016 - link

    Enjoyable rant, thanks! Reply
  • Wardrop - Friday, April 15, 2016 - link

    I'm sure Apple, who are obsessed with having a single cable for everything, would have been the ones who pushed Intel to support daisy chaining.

    Daisy chaining isn't a bad idea if implemented properly though. It should be passive to really work, as in, a physically unplugged device should be able to pass through a thunderbolt signal. Like a switch that opens and closes depending on whether the device is powered on or not.
  • galta - Friday, April 15, 2016 - link

    A little bit angrier than I would have expected, but correct in its essence.
    All these weird proprietary interfaces fail for a combination of high costs and lack of scale. All of us - or at least most of us - remember when microchannel was thought to be the future and we all know were it ended.
    As someone said before, Thunderbolt, as well as FireWire in its time, will make sense only for the 15 people who make 4k video editing on a 5k monitor on their Apples.
    The remaining will be more than glad to remain with USB.
  • zodiacfml - Friday, April 15, 2016 - link

    Same here. I never understood daisy chaining. I just dismissed it long ago that some people use the feature. Reply
  • ganeshts - Friday, April 15, 2016 - link

    Daisy chaining is a feature that is available.

    It is not mandatory that it needs to be used.

    Most people can just use a dock and it would have all the types of USB 3.x ports that they need.

    The beauty of Thunderbolt 3 is that it allows for just a single interface in sleek products, and it will have an ecosystem that allows people to pick and choose what interfaces they want in their system when 'docked' - that can't be said for proprietary interfaces developed by system vendors. (though I do agree that Thunderbolt being restricted to Intel-only systems is a bit of an issue in the long run - if AMD manages to claw back to performance parity with mid-range and higher Intel systems)
  • hyno111 - Friday, April 15, 2016 - link

    The ATTO and CrystalDiskMark result for SSD RAID is missing. Reply
  • ganeshts - Friday, April 15, 2016 - link

    My apologies. There was a CMS issue when we updated the HDD results. It is now fixed. Reply
  • epobirs - Saturday, April 16, 2016 - link

    Considering the main bottleneck here is going to be SATA, it seems like the box could have been implemented with USB 3.1 Gen 2 and delivered the same performance at lower cost. Even with two SSDs rather than platter drives, the best throughput after overhead should rarely exceed what USB 3.1 can handle.

    Down the road, a box with slots for, say, four U.2 SSDs, should really utilize Thunderbolt 3's bandwidth while still being small enough to consider portable. THAT would be worth spending a good amount for a professional user, being able to access live data or do very large backups at those speeds in a rig small enough to go on a location shoot comfortably.
  • ganeshts - Saturday, April 16, 2016 - link

    Definitely.. the performance of a single unit is very close to that of the bus-powered SanDisk Extreme 900 we reviewed before. However, this unit is clearly meant to introduce the benefits of Thunderbolt 3 to the market - DisplayPort output, daisy chaining with docks for extra functionality etc. The storage bandwidth from a single unit is not the main focus, as this is one of the first Thunderbolt 3 devices to be introduced. We will soon see high bay-count devices with Thunderbolt 3 at NAB next week - Accusys has already pre-announced a 12-bay one. Reply

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