Promise Pegasus2 review: The fastest (and priciest) external storage

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.

The Promise Utility comes in handy when you want to monitor the Pegasus2 or change its RAID configuration.
The Promise Utility comes in handy when you want to monitor the Pegasus2 or change its RAID configuration. Dong Ngo/CNET

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 MacBook Pro with the Pegasus2, you should make sure you you save your files before taking a break and exercise patience when you get back. The Pegasus2 now shares its power status with the host, which means that when the computer shuts down, the Pegasus2 will as well, and it will then turn back on by itself when the computer powers up. This is a huge improvement from the previous Pegasus models.

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.

CNET Labs' data-transfer scores -- Thunderbolt vs. external (in megabytes per second)
(Longer bars indicate better performance)
Read  
Write  
Promise Pegasus2 (RAID 5)
376.02 
361.92 
Promise Pegasus R6 (RAID 5)
177.53 
210.5 
Promise Pegasus R4 (RAID 5)
171.1 
150.47 
Promise J4 (RAID 0)
156.26 
200.31 
Promise J4 (RAID 1)
109.77 
110.71 
Promise J4 (JBOD)
95.24 
111.17 

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 Mac Pro to fully take advantage of its performance. And if you can afford the new Mac Pro, the cost of the new Pegasus2 seems quite manageable.

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.

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