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Promise Pegasus R4 review: Promise Pegasus R4

The Pegasus R4 Thunderbolt storage device from Promise Technology shows that Windows users can now enjoy the Thunderbolt peripheral standard, just as Mac users have for more than year.

Dong Ngo SF Labs Manager, Editor / Reviews
CNET editor Dong Ngo has been involved with technology since 2000, starting with testing gadgets and writing code for CNET Labs' benchmarks. He now manages CNET San Francisco Labs, reviews 3D printers, networking/storage devices, and also writes about other topics from online security to new gadgets and how technology impacts the life of people around the world.
Dong Ngo
7 min read

Promise Technology's Pegasus R4 is the first Thunderbolt storage device that works with the Windows platform right out of the box. But it wasn't always that way.

Promise Pegasus R4 (4TB)

Promise Pegasus R4

The Good

The <b>Promise Pegasus R4</b> offers very fast performance and works with both Windows PCs and Macs. The drive supports many different RAID configurations.

The Bad

The Pegasus R4 is expensive and relatively noisy, doesn't share its power status with the host machine, and doesn't come with a Thunderbolt cable. It has no other peripheral connections such as USB or FireWire, and performs noticeably more slowly than its big brother, the Pegasus R6.

The Bottom Line

The Pegasus R4 would be a very good investment for those who have a Thunderbolt-enabled computer, be it Windows PC or Mac.

The drive was actually first released together with the Pegasus R6 more than a year ago, when Thunderbolt first came out for Macs exclusively. Now the Thunderbolt standard is available and works virtually the same for both Windows and Mac platforms. From my trial with Intel's first Thunderbolt-certified motherboard, the switch of file system from HFS+ to NTFS (which can be easily done) is the only major thing you need to do to make any previously Mac-only Thunderbolt storage device work with Windows.

And you don't have to do that with the new Pegasus R4, since it also now comes preformatted for Windows. Effectively, it marks the end of an era in which Thunderbolt storage was exclusively for Mac.

Just because Thunderbolt is now available for Windows doesn't mean it's noticeably cheaper. The Pegasus R4 still costs about $1,000 for 4TB or $1,500 for the 8TB version, and you still need to buy the Thunderbolt cable separately. My guess is that the price of the technology as a whole will come down quickly since the Thunderbolt ecosystem has become a lot more popular, with more and more vendors joining.

That said, you're looking for a superfast storage device for use with your brand-new Thunderbolt-enabled computer, such as one that's powered by Intel's new DZ77RE-75K motherboard, the R4 will make a great investment. If you want more options in terms of storage space and other features, also check out the R6 and other Thunderbolt drives I've reviewed.

Drive type External Thunderbolt hard drive
Connector options Thunderbolt
Available capacities 4TB, 8TB
Product dimensions (LWH) 7.3x7.7x9.9 inches
Weight 15.3 lbs
Capacity of test unit 4TB
OSes supported Mac OS X 10.6.8 or later / Windows 7 or later
Software included WebPAM PROe (Windows) / Pegasus Utility (Mac)

Design and features
While some 5 pounds lighter than its big brother, the R6, the Pegasus R4 Thunderbolt drive is still huge, weighing about 15 pounds. This is to be expected since it has enough room to host four standard-size 3.5-inch hard drives. The drive looks very much like the R6, just two drive bays shorter. With an all-aluminum chassis and the white color, it looks more like a typical Mac device than one that works with Windows. But it does work with both, and the review unit is preformatted using NTFS, which is Windows' native file system.

On the back, the R4 comes with a standard power connector, the kind you normally find at the back of a desktop computer. This is very convenient since it means you can use the same type of power cable. There's a big ventilation fan and there are two Thunderbolt ports. Most Thunderbolt devices have two ports, one for connecting to a host computer and the other to another Thunderbolt drive. You can add up to five more devices this way in a daisy-chain setup. In my trials with a computer running Windows 7, the R4 worked well with other Thunderbolt devices, including Apple's Thunderbolt Display. I did need to install Apple's Boot Camp software for the display to work, however.

Note that, like all of the Thunderbolt devices I've reviewed, the Pegasus R4 doesn't come with the necessary Thunderbolt cable. You can get a long (6-foot) one from Apple for $50 or a shorter (3-feet) one from Belkin for $45.

On the front of the R4, in addition to the standard power button and status lights, you'll find the four drive bays. These bays are closed with a latch that's easily opened but prevents you from pulling a drive out accidentally. When a tray is pulled out, you can install a hard drive on it fairly easily with a standard Phillips-head screwdriver. My review unit came with four SATA 3 (6Gbps) hard drives of 1TB capacity each installed, making the total capacity of 4TB, or 3TB in the default RAID 5 setup. RAID 5 is the most recommended RAID setup for multiple-drive storage devices, since it balances performance and storage space while still offering protection against single hard-drive failure.

The Pegasus R4 also supports RAID 0, 1, 50, 6, 60, and 10. It comes with WebPAM PROe software for Windows and Pegasus Utilities for Mac. You can use either program to manage the drive, including changing its RAID setup, viewing the status of each hard drive, and so on. In my testing, the R4 took a very short time to change from one RAID to another, just a matter of minutes. I did find that WebPAM PROe could only be used to manage the Pegasus drive that was directly connected to the computer and not the others in a daisy-chain setup. Pegasus Utilities, however, can manage multiple daisy-chained Pegasus units at a time. This is not a big deal, however, since most of us wouldn't be able to afford more than one unit anyway. Also, Promise says it will soon fix this with a new version of the WebPAM PROe software.

Furthermore, unless you want to change the RAID setup, you won't need to use the software at all and there's no setup process to fiddle with. All you have to do is plug the R4 in and it works immediately.

I tested the Pegasus R4 with a new custom-built test PC that uses Intel's new DZ77RE-75K motherboard, a Core i7 CPU, 8GB of DDR3, and a 480GB Intel 520 series SSD. This is a very fast computer using one of the fastest solid-state drives (SSDs) on the market. Still, the top speed of the SSD, which is 6Gbps, is slower than the ceiling speed of the Thunderbolt standard, which is 10Gbps. With this setup I experienced what consumers would find in real-world usage. I tested the R4 only in its default RAID 5 setup, since this is the most popular and recommended RAID for a drive of its type.

Like other Thunderbolt drives, the R4 was benchmarked with two sets of tests. In the first set, it was stacked up against internal drives, both traditional hard drives and SSDs. In the second set, it was compared with other external devices that use USB 3.0, USB 2.0, FireWire, eSATA, and, of course, Thunderbolt connections.

In the tests against internal drives, first, I timed how fast the Pegasus R4 performed when copying data from one folder on itself to another, meaning the drive had to perform reading and writing at the same time. In this test, the R4 was much slower than the R6, scoring just about 100MBps. The R4 was more than twice as fast at copying data from another Thunderbolt drive, the R6, now registering about 240MBps. It was still slower than the R6, though faster than most other Thunderbolt drives.

The second set of tests measures the Pegasus R4's performance against more traditional external storage drives. For these tests we copied data directly from the test machine's internal SSD to show what a typical user could expect from a single R4 unit. In this test, the drive scored very well at 150MBps and 171MBps for writing and reading, respectively.

While not as impressive as its bigger brother, the Pegasus R4's performance will blow any Windows user who hasn't experienced Thunderbolt before. The drive was rather noisy during operation, however, and you can feel the vibration coming from its internal hard drives. You might want to leave it on the floor rather than on top of a desk for this reason.

Unlike other Thunderbolt devices I've seen except for the Pegasus R6, the Pegasus R4 doesn't share power status with the host computer, meaning it won't turn off when the computer is off or sleep and turns back on when the computer is powered up. You will need to manually turn it on or off, so don't leave it too far away from your reach.

Data transfer speed, Thunderbolt vs. internal (in MBps)
(Longer bars indicate better performance)
Self-read and write  
Promise Pegasus R6 (RAID 5)
Plextor PX-256M2S
OCZ Vertex 3
Promise Pegasus R4 (RAID 5)
Crucial M4
LaCie Little Big Disk SSD
OCZ Agility 3
Patriot Wildfire
WD VelociRaptor 600GB
Elgato Thunderbolt SSD
Seagate Barracuda XT
WD VelociRaptor 300GB

Data transfer speed, Thunderbolt vs. external
(Longer bars indicate better performance)
LaCie Little Big Disk SSD
Promise Pegasus R4 (RAID 5)
Elgato Thunderbolt SSD

Service and support
As with the R6, Promise Technology backs the Pegasus R4 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, especially one that costs thousands of dollars. On Promise's Web site, there's scant support-related information about its Thunderbolt-based products.

After more than a year of Thunderbolt being available exclusively for use with Macs, it's exciting that now Windows users can enjoy it. The Pegasus R4 marks the liberation of this superfast peripheral standard on the PC front. As a storage device, it will make a very good investment for anyone who can afford its premium pricing.

Promise Pegasus R4 (4TB)

Promise Pegasus R4

Score Breakdown

Setup 8Features 7Performance 8Support 7