Promise Pegasus2 review: the world's first Thunderbolt 2 RAID storage

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  • Price When Reviewed: R4 (4 x 2TB), £1,040 plus VAT . R6 (6 x 2TB), £1,540 plus VAT . R6 (6 x 3TB), £2,082.50 plus VAT . R8 (8 x 4TB), £3,165 plus VAT

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The Pegasus2 from Promise is the first Thunderbolt 2 peripheral to make its way into our test lab (we got a hands-on with LaCie's forthcoming Little Big Disk Thunderbolt 2, but we to test this properly before we can call it a review). The different versions offer between four and eight drives, up to 32TB of storage and cost from £1,040.

The Pegasus2 R4 chassis offers four drives, the Pegasus2 R6 six drives and the Pegasus2 R8 (surprise, surprise) eights drives. The first two offers the same setup as the first-generation Pegasus – with the R8 being a completely new option. What's the real difference is the addition of Thunderbolt 2 for faster data throughput – and therefore faster reading more layers of 2K and 4K video when editing, for example, on a computer with Thunderbolt 2 ports such as the new Mac Pro, the latest MacBook Pro, or HP's Z2Z420, Z620 and Z820 workstations, perhaps alongside AJA's Io 4K capture box.

How fast is Thunderbolt 2?

Technically, Thunderbolt 2 isn't faster than the first version of the standard – but it practice it delivers more. To get nerdy for a sec, it takes the original's two 10 Gbps bi-directional channels and combines them into a single 20 Gbps bi-directional channel. The amount of data able to move through a Thunderbolt connection hasn't increased, but the throughput of a single channel has been doubled. Thunderbolt 2 is backwards compatible with Thunderbolt devices, but those devices will run at the slower 10 Gbps speed.

The Pegasus2 R6 we received has six 7200rpm hard drives with 2TB of capacity each. The Pegasus2 is a hardware RAID that comes preconfigured as RAID 5 array, but can easily be changed to to RAID 0, 1, 10, or JBOD using the included software. The Pegasus2 has a black aluminum case to better match the design of the new Mac Pro and has two Thunderbolt 2 ports to allow for daisy chaining up to six compatible devices. Thunderbolt products with just one port, must sit at the end of a daisy chain, and having two ports gives you more flexibility, and have two Thunderbolt 2 ports means that you can connect more Thunderbolt 2 devices.

To see how fast the Pegasus2 R6 is, we ran a series of tests on a Mac Pro with Thunderbolt 2 and 2013 MacBook Air with Thunderbolt, with the drive in its default RAID 5 configuration. We ran the tests on a first-generation Pegasus R6 with the same drives as the Pegasus2. The Mac Pro tests showed the Pegasus2 hitting nearly 900MBps reading and writing in our 6GB files and folders test – about 20 per cent faster than the first generation Pegasus. The new Pegasus2 was 15 per cent faster writing and 18 per cent faster reading in our 6GB large file test than the older Pegasus.

Promise Pegasus2 R6: RAID 5 benchmarks

We retested the Pegasus2 in RAID 0 mode, a faster configuration than RAID 5, but without RAID 5's data redundancy. On the downside, if one of the six drives fails in a RAID 0 array, all of your data is lost. However, if you need maximum performance and using the drive for just the project you're working on currently (with your files also backed up elsewhere), then this is the set-up for you.

Promise Pegasus2 R6: RAID 0 benchmarks

These striped tests showed the Pegasus2 to be between 22 and 30 percent faster at writing data than the same device in RAID 5 mode. Black Magic Disk Test and AJA System Test both showed the RAID 0 Pegasus2 topping 1,100MBps writing and anywhere from 800 to 963Mps reading. Compared to a LaCie 5Big Thunderbolt drive also configured as RAID 0, we found the striped Pegasus2 to be about 50 percent faster writing and 20 percent faster reading than the LaCie, overall.

We also connected the Pegasus2 in its fast striped configuration to a late 2013 MacBook Air with the previous iteration of Thunderbolt. The Mac Pro write tests averaged about 40 percent faster than the Air tests, while the read tests varied from just 9 per cent faster than the Air in large file test to 29 per cent faster in the files and folder test to 40 per cent faster than the Air speeds in the AJA System test trials.

Promise Pegasus2 R6: RAID 0/MacBook Air benchmarks

Just for kicks we decided to try striping six SSD drives in the Pegasus2. There wasn't a huge difference in our file and folders tests, in fact writing could be a couple percent slower on those SSDs, but was averaging about 20 percent faster read speeds over the standard 7200 RPM drives that the Pegasus2 shipped with.

If you need storage with the fastest available throughput for your video post workflow – whether using a Mac or a Windows workstation – the Pegasus2 is the only game in town. While others will, no doubt, follow soon, the Pegasus2 is the only Thunderbolt 2-enabled drive available for purchase today. It offers six drive bays, dual Thunderbolt 2 ports and can be configured in many RAID varieties, and tops out at around 1,100MBps.

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