Promise Pegasus R6 review: Promise Pegasus R6

Our test computer used with the Pegasus R6 was a brand-new 2011 MacBook Pro running OS X Lion, with a SATA 3 (6Gbps) SSD. Although Thunderbolt's ceiling throughput speed is a much higher 10Gbps (about 1.2GBps), the transfer rate will be limited to the notebook's internal drive speed.

For this reason, in the tests against internal drives, we let the Pegasus work with the least involvement of the MacBook Pro's hard drive as possible. First, we timed how fast the drive performed when copying data within itself, from one folder to another. This means the drive had to perform both reading and writing at the same time. In this test, the Pegasus R6 registered 192.53MBps and 228.06MBps in RAID 5 and RAID 0, respectively--about five times the speed of the fastest SATA 3 internal hard drives and about 170 percent the speed of a typical SSD. After that, since we had two R6 units available, we performed the second test in this category by copying data from one R6 to the other, so that one of the units was doing the reading while the other was doing the writing. In this test, the devices registered much faster throughput at 323.8MBps and 353.2MBps for RAID 5 and RAID 0, respectively. This is about three times the speed of even the fastest SATA 3 hard drives and, again, some 170 percent faster than a SATA 3 SSD.

The second set of tests measures the Pegasus R6's performance against more traditional external storage drives. For these tests we copied data directly from the MacBook Pro's internal SSD, which imposes a throughput bottleneck. These tests show what a typical user can expect from the Pegasus R6, since it replicates how most of us would use an external storage device. In RAID 5, the Pegasus scored 210.5MBps and 177.5MBps for write and read, respectively. When we configured the drive in RAID 0 it did better, with 212.5MBps writing and 184.9 reading. These scores are about twice those of USB 3.0 devices and six to ten times that of even the fastest USB 2.0 external drive.

All in all, though we weren't able to experience even half of Thunderbolt's full 800MBps throughput, the Pegasus R6 is by far the fastest storage device we've ever seen. To put this in perspective, the device can finish transferring 50GB of data (equivalent to two Blu-ray Discs worth of content or five compressed full 1080p HD movies) in somewhere between just 3 and 5 minutes. Or it can do the same with a full CD's worth of data (about 800MB) in about 4 seconds at most.

While we were totally blown away and impressed by the Pegasus R6's performance, the drive's level of noise and vibration bothered us somewhat. This is likely due to the fact that it has six high-speed internal drives inside that all spin at 7,200rpm. The device isn't noisy enough to be a problem when tucked away under a desk, although it would be a shame to hide a good-looking drive like this. However, if you kept it on your work desk you'd quickly notice and be bothered by the vibration and noise.

Data transfer: Thunderbolt vs. internal (in MBps)
(Longer bars indicate better performance)
Unit to unit  
Self-read and write  
Promise Pegasus R6 (RAID 0)
Promise Pegasus R6 (RAID 5)
Plextor PX-256M2S
OCZ Vertex 3
Crucial M4
OCZ Agility 3
Patriot Wildfire
WD VelociRaptor 600GB
Seagate Barracuda XT
WD VelociRaptor 300GB

Data transfer: Thunderbolt vs. external (in MBps)
(Longer bars indicate better performance)
Promise Pegasus R6 (RAID 0)
Promise Pegasus R6 (RAID 5)

Service and support
Promise Technology backs the Pegasus R6 with a two-year warranty for all parts except for the fan and power adapter, which are covered for only one year. This is a rather short time period for a storage device that costs almost $2,000. On Promise's Web site, there's scant support-related information about its Thunderbolt-based products.

We were really impressed by the Pegasus R6's unprecedentedly fast performance, but were let down by its price and especially its lack of support for other peripheral interfaces. While you wouldn't buy the expensive Pegasus R6 to use exclusively with an older Mac or a Windows system, the fact that you can't connect it to those systems at all without an adapter is an annoyance. That's a minor complaint considering the Pegasus R6's performance, though. For Thunderbolt Mac owners with the capacity and storage-speed requirements to justify such a large expense, this drive is a worthwhile investment.

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