Why You Can Trust CNET Promise Pegasus2 review: The fastest (and priciest) external storage
CNET's full review of Promise's Pegasus2, the first external storage solution that supports the Thunderbolt 2 connection.
Editor's note: This review was updated on January 29, 2014 to address the power issues of the device that have been resolved. The rating has also been updated accordingly.
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Promise Pegasus2
The Good
The Bad
The Bottom Line
The Pegasus2 line is Promise's upgrade to the previous Pegasus lineup (including the
As a hardware RAID system, the Pegasus2 supports all RAID configurations available for the number of internal drives it houses, be it four drives (the R4 model), six drives (the R6), or eight (the R8). In my testing, the Pegasus2 R8 proved to be the fastest consumer-grade direct-attached storage solution to date. It almost doubled the performance of its predecessor, as you'd expect from the move to Thunderbolt to Thunderbolt 2. It's not perfect, though, since it's very expensive and, in my trial, would take a relatively long time to resume from sleep mode, making it a little inconvenient to use with a laptop.
But the Pegasus2 is definitely a desktop storage solution, and while for most consumers it's overkill, for professionals who need super-fast speed or archiving or real-time 4K video editing, its incredible performance is worth the hefty investment, which is between $1,500 and $4,600, depending on the model and capacities.
Familiar design, easy to set up The Pegasus2 family includes three models -- the R4, the R6, and the R8 -- that can house four, six, and eight internal drives, respectively. Housing standard SATA desktop hard drives of 2TB, 3TB, or 4TB, the Pegasus2 offers somewhere between 8TB and 32TB, depending on the models. The number of drives is the only difference among the three models. The more drives generally means more storage space and RAID options. I tested the R8 model, which is very representative of all three.
Other than the black color and the support for Thunderbolt 2, the new Pegasus2 lineup is almost exactly the same as the previous generation. Note that Thunderbolt 2 is the next generation of Thunderbolt, which offers a 20Gbps connection speed (twice that of Thunderbolt). Other than that, it shares the same kind of port and cable as Thunderbolt and is also backward-compatible with existing Thunderbolt devices.
On the front the Pegasus2 is an array of drive bays; each comes with a latch that enables you to quickly remove/install a standard SATA internal desktop hard drive. Each of the drive bays also comes with two LEDs to indicate the status of the drive on the inside. These lights are very helpful during a RAID rebuild or when you need to know which drive needs attention.
On the back there are two Thunderbolt ports. You just need to use one of these ports to connect to a computer with a Thunderbolt cable (a foot-long cable is included). The other port is to host another Thunderbolt device or a Mini DisplayPort monitor in daisy-chain setup. You can hook up to six devices to one host computer this way.
Also on the back, there's a large ventilation fan, but unlike in the previous generation, the new Pegasus2 was very quiet in my testing. It wasn't completely silent, but for a device of such large size, the amount of noise it produced didn't bother me at all.
There's nothing to setting up the Pegasus2. Out of the box, the device is set up in RAID 5 and preformatted in HFS+. Once connected to a computer via a Thunderbolt port (be it Thunderbolt or Thunderbolt 2), it's immediately available on your Mac, just like other external storage devices. The device is preloaded with Promise Utility software that you can use in case you want to monitor the storage device or to change it to a different RAID setup. The software itself is easy to use.
Advanced RAID, slow resumption from sleep mode Chances are you will be happy with the preconfigured RAID 5 setup, which balances among capacities, performance, and data safety. (Read more about RAID here.) But if you're not, as a hardware RAID system, the Pegasus2 supports all RAID configurations available to the amount of hard drives it hosts. The R8 for example, supports RAID 0, RAID 1, RAID 10, RAID 6, RAID 60, and RAID 50. The device takes a very short time to change from one RAID configuration to another.
You can also choose to have two separate RAID volumes within the Pegasus2. In this case, the Promise Utility software is handy because it helps you locate which drives belong to which RAID volume via the front LEDs.
While I was impressed with the RAID support, the Promise Pegasus2 R8's power management could use a little improvement. In my testing, the device would dismount when the host computer went into sleep mode, which is expected, and would take somewhere from 15 to 30 seconds to wake up and reconnect by itself once the host awoke. This means that in real-world usage, especially if you use a laptop such as the new
Most other Thunderbolt devices I've reviewed have much shorter wake-up time; some are nearly instantaneous. However, most of them are not hardware RAID systems, hence they are much less complicated than the Pegasus2.
Performance When I tested the original Pegasus R6, it was by far the fastest external storage device. Now the Pegasus2 R8 has almost double the speed.
I used a new late-2013 MacBook Pro with Retina Display for the testing. This is one of a few computers on the market that supports Thunderbolt 2 and is also equipped with a superfast PCIe-based solid-state drive (SSD). Chances are, however, that the computer might still be a bottleneck for a Thunderbolt2 connection. Nevertheless, the Pegasus2 R8 in a RAID 5 configuration offered outstanding data-transfer speed, with some 360MBps for writing and about 380MBps for reading. Note these are real-world sustained sequential data transferring speeds rather than the numbers that benchmarking software would give you, and were by far the fastest I've seen. In fact, as far as performance goes, the Pegasus2 is easily the fastest external storage solution to date.
(Longer bars indicate better performance)
 | Read | | Write |
Other than the odd power issue mentioned above, the R8 worked well in my testing and, considering its large fan on the back and the huge physical size, it was surprisingly quiet, and produced almost no vibration. This is a big improvement compared with the previous generation.
Conclusion
Expensive but incredibly fast, the Pegasus2 R8 is only suitable for professionals who need a superfast storage device for their movie editing or archiving project. They do need to have a new MacBook Pro or, better yet, the new
For general consumers, the Pegasus2, especially the R8 model, is massive overkill. If you really want speed, you can still probably get by just fine with the previous generation, the Pegasus R6, or R4, which are now much less expensive than they once were. If Thunderbolt 2 is a must, you can also wait for a while for other (hopefully more affordable) products from other storage vendors.