Delivering up to 1 GB/s data of throughput and the ability to communicate over PCI Express externally, it's no surprise that Thunderbolt has the attention of enthusiasts today. Those same savvy buyers see that the technology still bears a prohibitively high price premium, though, and decry its lack of value. If you aren't yet familiar with Thunderbolt and want a low-level lesson on it, check out Everything You Need To Know About Thunderbolt.

Nevertheless, several Thunderbolt-based external storage solutions are now available with the potential to nearly double the peak performance of today's most popular interfaces. The question is: are vendors able to populate these enclosures with the right hardware to enable blazing-fast transfers?
Finding Its Place
We certainly understand if you're reluctant to spend extra money on a new and unproven connectivity standard that looks like it's being set up to replace USB. But take solace in Intel's insistence (for now) that Thunderbolt is meant to complement USB 3.0 and not replace it. Although the two interfaces appear at odds, they're decidedly ideal in very different ways and for equally disparate applications.
USB 3.0 does, for example, enable impressive performance across a bus rated for 5 Gb/s. However, its inefficiencies knock what, on paper, appears to be a 500 MB/s interface down far below that theoretical maximum. As an interface for storage, Thunderbolt's 10 Gb/s (1 GB/s) peak has no trouble nudging USB 3.0 from its pole position.
It's perhaps more accurate to think of Thunderbolt as the spiritual successor to the FireWire standard, aimed at users with high-end applications unable to compromise performance—and willing to pay top dollar for it.

And like FireWire 800, which was exorbitantly-priced when it debuted, today's Thunderbolt-based adapters cost more than $150 and require expensive cabling that isn't included. Intel says that it's committed to bringing down the cost of second-generation Thunderbolt controllers and cables, hopefully allowing the technology to dangle within reach of value-conscious customers sooner rather than later.
A large number of Thunderbolt-related product announcements at this year's Computex give us some indication that a flood of products should be emerging soon. But there are already dozens of Thunderbolt-based storage devices available. We gathered up nine and put them to the test.

| Elgato Thunderbolt SSD | 120 GB (10024012) | 240 GB (10024024) |
|---|---|---|
| MSRP | $420 | $699 |
Elgato is well known in the Mac world for its capture card products, and is now jumping into the storage market with the Thunderbolt SSD.
One significant limitation of this drive is that it hosts a single Thunderbolt port (a side effect of its Intel Port Ridge controller), which means you have to put the Thunderbolt SSD at the end of a daisy chain or use it on its own. This is an issue if you only have one Thunderbolt port and are already using a mini-DisplayPort adapter to drive a monitor; you're forced to choose between one device or the other. There is no way around that issue, as we haven't seen any mini-DisplayPort adapters with Thunderbolt pass-through.

The Thunderbolt SSD's thick aluminum case makes it rather hefty, but it's actually fairly simple inside. Aside from Intel's DSL2210 controller, you find an ASMedia ASM1061 SATA 6Gb/s controller on the PCB and an older SanDisk 3Gb/s 240 GB Ultra SSD. Based on SandForce's first-gen technology, SanDisk’s Ultra-series drives are functionally similar to OCZ's Vertex 2.

Elgato’s decision to use a SATA 3Gb/s-class SSD really impacts the device's benchmark results. As you can see, sequential read and write speeds top out at ~250 MB/s. But that's not all. Testing with incompressible data (SandForce's Achilles' heel) drops sequential write throughput to ~90 MB/s, making the Thunderbolt SSD ill-suited for working with multimedia files. Random reads and writes aren’t impressive either, unfortunately. SandForce’s first-generation controller logic performs rather poorly in those two disciplines, explaining why we see random access numbers peaking near 100 MB/s.
Upgrading the Thunderbolt SSD's internal drive voids its warranty. If you want to throw a faster SSD in there anyway, be aware that Elgato employs a tamper-resistant tar-sealed hex cap that discourages opening the case. In its stock configuration, this is a good example of a drive that lacks the composition to fully exploit the potential of Thunderbolt. And yet, after the cost of SanDisk's roughly $130 drive (in the 120 GB model), you're still paying close to $300 more to get 3 Gb/s performance in Thunderbolt trim.

| G-RAID Thunderbolt | 4 TB (0G02289) | 8 TB (0G02272) |
|---|---|---|
| MSRP | $700 | $1000 |
G-Technologies is a subsidiary of Hitachi Global Storage Technologies, which was acquired by Western Digital a few months ago. We're told there are no plans to discontinue Hitachi GST's products. But, should that occur, Western Digital will continue to honor warranty coverage, alleviating concerns over buying a G-Technologies device.
The G-RAID Thunderbolt is housed in a silver-colored MacBook Pro-like aluminum shell, with two ports located on the back for daisy chaining, along with a power switch and fan exhaust port. The combination of an active cooler fan and an aluminum housing seems fairly effective for dissipating the heat from Intel's Thunderbolt controller and the installed hard drives. At idle and during our streaming write tests, the unit remained cool, and we're happy to say its fan runs more quietly than the mechanical disks.

The two internal 4 TB 3.5” Hitachi Deskstar 7K4000 hard drives occupy three-quarters of the length of the unit, and both repositories are positioned near the front grill. Not all G-RAID Thunderbolt units feature the configuration we're reviewing today. G-Technology also offers 4 TB (2 x 2 GB) and 6 TB (2 x 3 GB) versions employing Hitachi’s Deskstar 7K2000 and 7K3000 family, respectively. All three capacities are rated for similar performance, so your only real decision is how much storage space you need.
Upgrading the installed hard drives on your own voids the warranty, so it may be wise to err on the side of caution and buy bigger if you anticipate a rapidly-growing library of music or videos eating up capacity quickly. There is no way to sneak around this restriction, as a tamper-resistant sticker hides one of the screws required to disassemble the chassis.

Unlike the Elgato unit, G-Technology uses Intel's CV82524EF/L Thunderbolt controller, equipped with four channels, to facilitate support for daisy chaining. Also unlike the Elgato unit, the G-RAID Thunderbolt forgoes ASMedia's storage controller in favor Marvell's 88SE9182 SATA 6Gb/s solution.
There is no hardware-based RAID controller on-board. So, you have to configure RAID via software either in Windows or using OS X's Disk Utility. That's an important note, since G-Technology incorrectly claims that this device supports hardware-based RAID 0 on its product webpage.

Configured manually to operate in RAID 0 mode, the G-RAID Thunderbolt reaches sequential read speeds of ~325 MB/s, regardless of queue depth. Sequential writes, on the other hand, start out at ~270 MB/s and jump to 320 MB/s once there are sixteen concurrent operations.
Sequential write performance hangs steady at 155 MB/s in RAID 1, and sequential reads climb from 50 MB/s to ~160 MB/s.

| SKU | 9000310 | 9000106 | 9000107 | 9000243 |
|---|---|---|---|---|
| RPM | 5400 RPM | 7200 RPM | 5400 RPM | SSD |
| Capacity | 1 TB | 1 TB | 2 TB | 240 GB |
| Devices | 2 x 500 GB | 2 x 500 GB | 2 x 1 TB | 2 x 120 GB |
| Price (MSRP) | $380 | $450 | $549 | $849 |
| Market Price | $350 | $390 | $500 | $735 |
LaCie’s Little Big Disk (LBD) is available in four trims: 1 TB (2 x 500 GB, 5400 RPM), 1 TB (2 x 500 GB, 7200 RPM), 2 TB (2 x 1 TB, 5400 RPM), and 240 GB (2 x 120 GB, SSD). The 240 GB model, which is what LaCie submitted for review, is unquestionably the most interesting. It's the first Thunderbolt-based device we have seen with SSDs in RAID. That's perfect for pushing the interface's performance, providing the company picks the right drives.
LaCie touts the Little Big Disk as a "portable powerhouse," and SSDs drive that message home quite effectively. However, we do end up with critical feedback to pass along. Contrary to LaCie’s product photos, the Little Big Disk requires a separate AC adapter for daisy chaining because Thunderbolt, in its current form, does not supply enough power to run everything off of bus power.

Our enthusiasm is further dampened by the fact that LaCie chose to employ Intel’s 120 GB SSD 320. Don't get us wrong, we've found the SSD 320 to be incredibly reliable. It's just not a great-performing drive. You'd get better benchmarks results from any number of more modern 6 Gb/s-capable SSDs. But before you consider a do-it-yourself replacement, bear in mind that you'd be voiding LaCie's warranty. Four screws on the back of the drive are resin-coated, making it easy to tell if the chassis is opened.

All of LaCie's Little Big Disk models employ the same Intel CV82524EF/L Thunderbolt and Marvell 88SE9182 SATA controllers.

Queue depth appears to have no impact on performance, which is good news if you don't have one of those rigorous storage workloads needed to extract peak performance from many SSD-based products.
In RAID 0, sequential reads even out at ~470 MB/s, while writes peak around 250 MB/s. Using relatively low-capacity SSDs makes it hard to imagine a scenario where RAID 1 would make sense, but we generated those numbers anyway, if only as an interesting comparison to what RAID 0 does for throughput. And, as expected, when we limit the Little Big Disk to the capabilities of a single SSD 320, its sequential reads max out at ~250 MB/s, while sequential writes fall to ~125 MB/s.

Unfortunately, the SSD 320's random performance results are fairly modest, so the numbers we see aren't as spectacular as what you might otherwise expect from a modern SSD. The 4 KB random reads slowly climb from ~20 MB/s to ~130 MB/s, with no correlation to RAID configuration. We see that 4 KB random writes max out at 100 MB/s in RAID 0; RAID 1 achieves up to ~50 MB/s.

| SKU | 9000191 | 9000192 | 9000193 |
|---|---|---|---|
| RPM | 7200 RPM | 7200 RPM | 7200 RPM |
| Capacity | 4 TB | 6 TB | 8 TB |
| Devices | 2 x 2 TB | 2 x 3 TB | 2 x 4 TB |
| Price (MSRP) | $600 | $750 | unreleased |
| Market Price | $570 | $715 | unreleased |
LaCie’s 2big external RAID enclosure, featuring hot-swappable bays, is a much better option for enthusiasts looking for a little flexibility without jeopardizing warranty coverage. The 2big isn't a clear winner over LaCie's Little Big Disk in every way, though. It's larger and less portable, whereas the Little Big Disk leverages 2.5" drives to keep its form factor much more compact. But that shouldn't be a deterrent; the 2big accepts higher-capacity 3.5" storage and is deliberately designed to be stationary. If you need mobility, LaCie has more purpose-built solutions (like the Little Big Disk).
As with pretty much all of the Thunderbolt-based products we're looking at today, the 2big isn't an inexpensive piece of hardware. LaCie's 4 TB model (9000191) sells for $600, or ~$0.15 per GB. Jumping to the 6 TB model (9000192) increases the price to $750, but reduces the cost per-gigabyte to ~$0.09. Fortunately, both available versions can be found online for a bit less.

Regardless of the capacity point, LaCie utilizes Seagate's 7200.14 Barracuda (ST3000DM001) family inside its 2big models. That's a respectable choice, as the 7200.14 happens to be a decent middle-of-the-road performer.

The 2big employs the same Intel CV82524EF/L and Marvell 88SE9182 configuration as the Little Big Disk, but it integrates beefier power circuitry to support 3.5" disk drives.

Expect to see sequential read results somewhere in the neighborhood of 400 MB/s from the 2 big in a RAID 0 configuration. Writes level off around ~290 MB/s.
Protecting your data with RAID 1 nearly halves those performance numbers.

| Promise | Pegasus R6 6 TB | Pegasus R6 12 TB |
|---|---|---|
| Devices | 6 x 1 TB | 6 x 2 TB |
| Hard Drive | Hitachi 7K1000.D | Hitachi 7K3000 |
| Price (MSRP) | $1799 | $2499 |
Sporting six hot-swappable bays, Promise’s Pegasus R6 is the top dog when it comes to performance-oriented Thunderbolt-based storage solutions. Intel and its partners commonly use this device to demonstrate what the technology is capable of achieving, and the R6's high price makes it even more exclusive. The entry-level 6 TB (6 x 1 TB) model will set you back $1800, and the 12 TB version commands a $2500 price tag.
You get what you pay for, though, and the Pegasus R6 demonstrates its suitability in business-class environments with a serial port for uninterruptible power supply support at the back of the chassis.

Promise sent us its 12 TB Pegasus R6, employing six 2 TB Hitachi 72K300 hard drives (the 6 TB variant is equipped with Hitachi’s 7K1000.D series). The drive bays are well-designed, featuring sturdy aluminum face plates and large release buttons that make it easy to swap storage out in the event of a disk failure.

The picture above, turned upside-down for better clarity, shows the interior of the Pegasus R6, where we find a 250 W power supply driving a motherboard with PMC-Sierra’s PM8011 PCIe SAS 6Gb/s RAID controller. The PM8011 is actually an eight-lane controller. But because Thunderbolt only enables a PCIe x4 uplink, the other four lanes aren't used.
It's interesting that Promise populates the SAS controller with SATA-based hard drives, though not entirely surprising given the premium SAS-capable disks would have added. You can look at the daughtercard's connectors, though, and see the full SAS interface that accommodates SATA disks, too. SAS 6Gb/s and SATA 6Gb/s both enable similar data rates, so there's no concern over compromised performance. We think that Promise's decision to arm its enclosure with SATA storage was the right one. However, should the company wish to offer a version of its R6 with nearline SAS drives in the future, that could become a possibility.
The R6 supports RAID 0, 1E, 5, 6, 10, and 50. However, we're narrowing our focus to the three configurations we feel are most attractive on a device like this: RAID 0, RAID 1E, and RAID 5.

The R6 really stretches its legs when we measure sequential read performance in RAID 0. It falls just 50 MB/s short of the 1 GB/s barrier at a queue depth of 16! If redundancy is more important to you than blistering speed, RAID 1E operates effectively as three RAID 1 arrays, which is why sequential read performance falls to ~315 MB/s. RAID 5 is a fair compromise, enabling block-level striping with distributed parity. We see sequential reads top out around ~780 MB/s in that arrangement.
This is the only device we're reviewing with performance characteristics that look a little different under OS X than Windows, and there's a reason why. Originally, Thunderbolt allowed device I/O and display signaling to share bandwidth over both bi-directional channels. However, in the summer of 2011, Apple and Intel decided to put device I/O on its own channel in order to preserve the display's signal integrity under heavy workloads.
Prior to that, we were able to achieve close to 920 MB/s in RAID 0 on our 15” MacBook Pro. However, since we "upgraded" to a 13.3” MBP, our new results seem to suggest a ceiling around ~800 MB/s. Promise tells us it sees slightly better performance on PCs, but the delta should only be a few percent at most. Our numbers require more Mac-specific testing, since we don’t know whether it was the update or our system to blame.

| Promise | Pegasus R4 4 TB | Pegasus R4 8 TB | Pegasus R6 6 TB | Pegasus R6 12 TB |
|---|---|---|---|---|
| Devices | 4 x 1 TB | 4 x 2 TB | 6 x 1 TB | 6 x 2 TB |
| Hard Drive | Hitachi 7K1000.D | Hitachi 7K3000 | Hitachi 7K1000.D | Hitachi 7K3000 |
| Price (MSRP) | $1149 | $1799 | $1799 | $2499 |
The four-bay version of Promise's Pegasus is more affordable, offered in 4 and 6 TB configurations. You'll pay $1150 for the 4 TB R4 (versus $1800 for the entry-level 6 TB R6). Aside from its lower price and two-fewer drive bays, there's very little else distinguishing the R4 and R6 families. Promise even uses the same Hitachi Deskstar hard drives in them both.

Crack open the R4 and you find the same motherboard and power supply seen in the R6.

Eliminating two drive bays from the R6 does impact performance, though. In RAID 0, the R4's sequential reads top out at ~635 MB/s, representing a closet-to 33% drop from the R6. Sequential writes in RAID 0 only drop about 18%, from 635 MB/s to 535 MB/s.
RAID 1E and RAID 5 performance are mostly unchanged. The only exception is that sequential reads in RAID 5 peak at ~460 MB/s, about a 70% drop from the R6’s 780 MB/s.

Promise plans to release an SSD-based version of the R4, but has not yet decided on a specific drive model to use yet. We are told that Intel's 240 GB SSD 520 is a strong contender due to the company’s stellar reputation for reliability and the zippy performance delivered by SandForce's second-generation controller.
Promise does not anticipate selling an SSD-based R6, stating the added cost of six SSDs would would push the price of the R6 beyond what the market will bear. We don't have an estimate for what the R4 with solid-state storage will cost, either, so we were forced to create our own estimate. Using the current 4 TB R4 as a baseline, we assume the 1 TB Hitachi 7K1000.D Deskstar hard drives are about $100 each, with the chassis and components totaling about $750. A single 240 GB Intel SSD 520 runs just north of $300, so a four-SSD variant of the current R4 could conceivably weigh in under $2000.
What this quad-SSD R4 variant might offer will depend on what you compare it to. Next to the R6, its benefits are likely to be limited. In theory, sequential performance should speed up by 5-10% (50-100 MB/s), while random I/O improves by an order of magnitude. Achieving better random throughput is important for certain applications that a hard drive-based solution simply cannot address. However, LaCie's Little Big Disk is more effective with its two SSD 320s than Promise's R4 armed with four SSD 520s when it comes to random performance.

The SSD-based R4's throughput matches what you can achieve using a hard drive-based R6. However, that performance gain costs lots of capacity. Even sporting 240 GB drives, the R4 tops out under 1 TB of space. That's nowhere near enough room for data-dense multimedia applications that chew up multiple terabytes.
Perhaps the characteristics of solid-state storage make this particular R4 more attractive, though. If you have production equipment operating in a vehicle, for example, or are constantly moving drives from one place to another, SSDs prove far more resilient against physical shock. They also run a lot cooler and use a lot less power.

| Models | MSRP | Market Price |
|---|---|---|
| GoFlex Desk Thunderbolt, 3 TB (old bundle: STBC3000102) | $410 | $370 |
| GoFlex Desk Thunderbolt Adapter (STAE122) | $190 | $190 |
| 3 TB Backup Plus FireWire 800/USB 2.0 (STCB3000100) | $210 | $170 |
| 3 TB FreeAgent GoFlex USB 3.0 (STAC3000102) | $180 | $140 |
Seagate recently announced its Backup Plus, a refresh of its external GoFlex storage line-up. As described by Seagate, the company's new Backup Plus drives feature the Seagate Dashboard, a one-click backup interface supporting both Macs and PCs that also enables sharing and saving photos to and from popular social networking sites.
In concert with the Backup Plus introduction, we're also seeing a refresh of Seagate's product bundles, including the 3 TB GoFlex Desk Thunderbolt that includes a Backup Plus hard drive. Aside from new software features, however, very little changes. Seagate is still using its same generation of Barracuda 7200.14 disks.
Don't feel like you have to wait for one of the new bundles to come out before making a purchase, though. If you look at the prices, it's a little cheaper buy the Thunderbolt adapter after grabbing one of Seagate's older offerings compatible with USB 3.0, for instance. In fact, you don't really even need a GoFlex hard drive to use with the Thunderbolt adapter. Because Seagate employs a standard SATA connection between the two devices, you could even drop a bare disk on the dock and it'd work. To prove our point, we even installed a Blu-ray drive onto the adapter.

Internally, the GoFlex Desk Thunderbolt Adapter consists of a motherboard hosting ASMedia's ASM1061 SATA controller and a PCI Express x1 slot. Intel's CV82524EF/L Thunderbolt controller is soldered onto an add-in card that drops onto the small board. Unfortunately, you can't yank out the x1 card and plug it into your PC. We tried, failed, and then asked. That's just not how it works.

Because we're measuring the performance of a single hard drive, the GoFlex Desk Thunderbolt's sequential read and write performance levels off at ~190 MB/s, regardless of queue depth.

| Models | MSRP | Market Price |
|---|---|---|
| GoFlex Ultra-Portable Thunderbolt, 1 TB (old bundle: STBA1000104) | $280 | $270 |
| GoFlex Ultra-Portable Thunderbolt Adapter (STBA1000104) | $100 | $100 |
| 1 TB Backup Plus Ultra-Portable USB 3.0 (STBU1000100) | $140 | $110 |
Similar to Elgato's Thunderbolt SSD, Seagate's GoFlex Ultra-Portable Thunderbolt Adapter employs an Intel DSL2210 controller, meaning it can only be used at the end of a daisy chain or on its own. The good news is that it only costs $100, making the portable adapter a lot less expensive than the desktop version.
The Ultra-Portable Thunderbolt bundle is also in the middle of a product refresh. But it is worth noting that Seagate’s modular product formula simplifies an upgrade down the road. You can buy the storage now (in the form of a USB 3.0-equipped drive) and upgrade to Thunderbolt later when the technology stands to benefit you more.

Based on our performance numbers, it is frankly difficult to imagine buying the GoFlex Ultra-Portable Thunderbolt Adapter as an upgrade. Sequential read and write speeds top out around 110 MB/s, which is already roughly on par with the version sporting USB 3.0.
We can more easily imagine using this adapter in conjunction with a fast SSD, though. If you were attaching a solid-state drive to a desktop, you'd simply connect it internally to a SATA port. But most mobile systems don't give you that option. Thus, the GoFlex Ultra-Portable Thunderbolt adapter becomes an easy way to add a very fast 2.5” SATA-based device to a Thunderbolt-enabled notebook, while achieving near-native performance.


| My Book Thunderbolt Duo | 4 TB | 6 TB |
|---|---|---|
| SKU | WDBUPB0040JSL-NESN | WDBUPB0060JSL-NESN |
| Devices | 2 x 2 TB | 2 x 3 TB |
| Hard Drive | WD20EARX | WD30EZRX |
| MSRP | $600 | $700 |
| Market Price | $518 | $590 |
Like LaCie’s 2big, Western Digital’s My Book Thunderbolt Duo gives you the option to replace internal storage without invalidating its warranty.
We have some seen confusion surrounding Western Digital's cooling design, though. Some users complain about its plastic enclosure, claiming it runs too hot. But company representatives say that's by design. A small fan draws in cool air from the bottom of the unit, and convection serves to cool the internal components before venting out the top. This helps explain why the My Book Thunderbolt Duo's exhaust temperatures are routinely 10-15o F higher than LaCie’s 2big, which also enjoys the benefit of an aluminum enclosure for dissipating heat. Its mechanism explained, the only drawback to Western Digital's design is that you can't stack drives on top of each other (or other components on top of a My Book).

Assurances from Western Digital aside, we stress-tested these drives with more than 100 hours of intensive write operations to try getting them to pop, and didn't see a single failure. Although they don't have the 2big's sexy aluminum enclosure, a plastic housing is less expensive to manufacture, reflected in the My Book Thunderbolt Duo's price tag.

Internally, Western Digital's implementation differs from LaCie's in that it employs ASMedia's ASM1061 SATA controller.

Sequential read and write performance tops out just over 240 MB/s in RAID 0 and 125 MB/s in RAID 1.
When it comes to Thunderbolt and storage performance, A/V professionals should be particularly happy with the interface. As you've seen in our product spotlights, sequential throughput is quite often exceptional. By emphasizing the speed at which 128 KB blocks of data can be pushed through the interface, we got an accurate picture of how each submission is able to do its job.
It's not our intention to shun random-access performance entirely. However, none of these solutions are going to deliver impressive IOPS rates. If you don't believe us, check out the second page of Everything You Need To Know About Thunderbolt. A typical 3.5” rotating hard drive is good for somewhere between 200 and 300 IOPS in random read/write workloads, which is less than 1 MB/s when you're dealing with 4 KB blocks. Even when you stripe six 3.5” desktop-class drives, the result is less than 10 MB/s of random reads.
That's not a problem with SSDs, which are capable of up to 80 000 IOPS, in the case of a Vertex 3. That's why we only presented random benchmark results for the SSD-based Thunderbolt solutions.
Thunderbolt is operating system-agnostic. But because Apple had a one-year head-start with the technology, more of its platforms are already equipped with the requisite controller hardware to support Thunderbolt. We ran our benchmarks on both Macs and PCs, achieving identical performance except where we noted otherwise. There are some PC-oriented problems tied to hot-plugging and daisy-chaining, but they don't affect performance, and Intel claims that it's working to help resolve them.

Installing vendor-specific SATA controller drivers delivered a ~1-3% performance boost compared to using Windows 7's generic ACHI driver.
| Test Hardware | ||
|---|---|---|
| System | Desktop | MacBook Pro 8,1 |
| Processor | Intel Core i5-2400 (Sandy Bridge), 32 nm, 3.1 GHz, LGA 1155, 6 MB Shared L3, Turbo Boost Enabled | Intel Core i5-2430M (Sandy Bridge), 32 nm, 2.4 GHz, 3 MB Shared L3, Turbo Boost Enabled |
| Motherboard | MSI Z77A-GD80 | - |
| Memory | Kingston Hyper-X 8 GB (2 x 4 GB) DDR3-1333 @ DDR3-1333, 1.5 V | Crucial 8 GB (2 x 4 GB) DDR3-1333 |
| System Drive | OCZ Vertex 4 256 GB SATA 6Gb/s | |
| Secondary Drive | OCZ Vertex 3 256 GB SATA 6Gb/s | |
| Graphics | Palit GeForce GTX 460 1 GB | Intel HD Graphics 3000 |
| Power Supply | Seasonic 760 W, 80 PLUS Gold | - |
| System Software and Drivers | ||
| Operating System | Windows 7 x64 Ultimate | |
| DirectX | DirectX 11 | - |
| Driver | Graphics: Nvidia 270.61 RST: 11.0.0.1032 | - |
| Benchmarks | |
|---|---|
| Iometer 1.1.0 | # Workers = 1, 4 KB Random: LBA=8 GB, varying QDs, 128 KB Sequential |
| Transfer Tests | Copy From Secondary Drive, Proprietary Benchmark |
Because Thunderbolt is so well-suited to the data-intensive needs of A/V professionals, we thought it fitting to measure the speed at which a 31 GB Blu-ray movie rip could be written to each device.

When it comes to raw sequential performance, a striped array communicating over Thunderbolt is formidable indeed. Promise's Pegasus R4 and R6 lead the pack, both units finishing the write task in 1:45. If you're willing to give up a lot of capacity in the name of solid-state storage, four SSD 520s in the R4 drop that completion time to 1:28.
LaCie’s 2big trails by only 10%, but it impressively outperforms the company's own SSD-equipped Little Big Disk. That shouldn't come as a surprise, though. According to Iometer, the 2big's hard drives outmaneuver the SSD 320s by ~15-25 MB/s in sequential read operations. There's a good lesson in there somewhere. Don't expect that, just because a device is armed with SSDs that it'll automatically move data around faster than an enclosure with hard drives.
Indeed, Western Digital's hard drive-based My Book Thunderbolt Duo matches the performance of LaCie's Little Big Disk, and the G-Technologies G-RAID Thunderbolt 8 TB follows behind by only a few seconds.

Even the performance of a single-drive Thunderbolt-based device should impress the folks who aren't interested in a multi-disk RAID enclosure, best illustrated by Seagate’s GoFlex Desk Thunderbolt Adapter’s small victory over the USB 3.0 version.
It's particularly notable that even a Thunderbolt link with multiple peripherals daisy chained onto it has sufficient bandwidth to enable full performance from downstream devices. Meanwhile, USB 3.0 slows down for every component added to a hub.
A quick breakdown of the single-drive observations:
- With a 3.5” hard drive, Thunderbolt proves faster than USB 3.0 by a small margin.
- With a 3.5” hard drive, the benefit of Thunderbolt compared to USB 3.0 increases as you add devices to the same interface.
- With a slower 2.5” hard drive, Thunderbolt performs about on par with USB 3.0. A daisy chainable device is needed to demonstrate an advantage.
- Regardless of the hard drive, Thunderbolt performs faster than FireWire 800 and USB 2.0 by huge margins.
- Do not assume an SSD in an external enclosure is going to be faster than hard drives.
We focused most of our attention on the performance of sequential transfers. However, not all sequential tests are the same. You might move a large move file 128 KB at a time. But a folder filled with different-sized files can still be moved sequentially using smaller blocks, too. The performance you see from such a mixture is not necessarily consistent with what we just saw writing a huge Blu-ray rip to each Thunderbolt device.

Testing our RAID 0-based enclosures, our rankings are largely the same as the previous page. The only exception is LaCie’s Little Big Disk, which outperforms the 2big, G-RAID Thunderbolt, and WD My Book Thunderbolt Duo.

Thunderbolt's benefits become clearer using single-drive devices with 3.5" disks. Moving a single file to the GoFlex Desk resulted in similar performance from Thunderbolt and USB 3.0. However, USB doesn't support command queuing. As a result, Thunderbolt takes a 22% lead when transferring bulk files. This is also an advantage when it comes to editing video, as data caching behaves similarly.
We see Elgato’s Thunderbolt SSD surge back because it's no longer getting hammered by incompressible data. Consequently, it matches the performance of Seagate's GoFlex Ultra-Portable (Thunderbolt or USB 3.0).

We know that Thunderbolt's maximum sequential throughput is close to the 1 GB/s mark, and Promise's Pegasus R6 has the unique distinction of saturating this new interface using six 3.5" hard drives. But it'd be wrong to assume that it takes $2000 to get the most out of Thunderbolt. Unlike USB, Thunderbolt was designed so that multiple devices can operate in parallel and still achieve their peak performance. You can get that same 1 GB/s from three or four peripherals doing 250 to 300 MB/s each.
This critically important advantage doesn't get enough attention. With USB, the interface bottlenecks performance, not the devices themselves. As an example, if you burn a DVD on a USB 2.0-based writer and write to a thumb drive, those conflicting operations could yield a useless coaster. Although USB 3.0 facilitates a lot more headroom, the technology is similar, and bottlenecks remain probable.
Thunderbolt alleviates interface limitations. Yeah, one LaCie 2big can "only" hit 350 MB/s in sequential reads. But a second 2big in the same chain can hit 350 MB/s, too. You can use those two drives, plus something like BlackMagic’s Intensity Extreme (a Thunderbolt-based external capture device used by professionals to edit 1080p content) and not have any of those three devices stepping on each others' toes. If that matters to your application, then spending money on high-end hardware probably isn't your top concern.
For everyone else, though, Thunderbolt does still face a big pricing problem. Even one 4 TB 2big at almost $600 reflects heavy mark-up. If you have room for a quartet of 1 TB disks inside your case, they'd only run about $360.
Those fat premiums will hopefully slim down over time. But even at a more attractive price, several of the devices in our round-up are haunted by other issues that call into question their utility. Elgato’s Thunderbolt SSD, for example, suffers from poor throughput because it employs an SSD based on SandForce's first-gen controller technology. That's fine for moving personal data around. But it's far less adept at handling encoded media files. Surely, a $420 price tag for 120 GB of capacity doesn't help. Seagate’s GoFlex Ultra-Portable Thunderbolt Adapter is only able to operate as an endpoint device. You can use it in a daisy chain, but you have to give up the potential for outputting to a display with a mini DisplayPort adapter.
Western Digital’s My Book Thunderbolt Duo competes directly with LaCie's 2big, but is hurt by slower drives. The thing is, the My Book Thunderbolt Duo costs $50 less than the 2big, which is a reasonable trade-off, so long as you're also able to accept the plastic case. They both offer notable value, earning LaCie's 2big 6 TB and Western Digital’s My Book Thunderbolt Duo 6 TB our 2012 Recommended Buy Award.

If you'd rather manage just a single Thunderbolt-based device (count us in), you can't ignore the incredible performance enabled by Promise's Pegasus R4 and R6. The SSD version of the R4 isn't final yet, but we're certainly impressed with our early preview.
Performance and value are still vital criteria, though. The least-expensive Pegasus R4 costs 33% less than the R6, and sacrifices the same margin of sequential read performance. However, both units serve up identical sequential write speeds, making the R4 a better value. That also earns Promise's Pegasus R4 our 2012 Recommended Buy Award.