Monthly Archives: December 2013

Promise Pegasus J4 Review

(Updated 12/05/2013)

Review Notes:

  • This article is a continuation of the “USB 3.0 Hub RAID” Study. We received our copy of the “Promise Pegasus J4” and tested it using the same methodology as the “USB 3.0 Hub RAID” Study.
  • The equipment used in this review is the same equipment used in the “USB 3.0 Hub RAID” Study with the exception of removing the four 1TB, 7200rpm drives from their USB 3.0, bus powered enclosures and installing them in the “Promise Pegasus J4”. This arrangement negates the use of a USB hub and requires the use of the Thunderbolt port on the computer rather than one or both USB ports. This procedure ensures a fair comparison with the same drives, computer and software used in each test.
  • The drives were configured RAID 0 and were half filled with 2TB of data while in their “USB 3.0 Hub RAID” configuration. After removing the drives from their enclosures and installing them into the “Promise Pegasus J4” the RAID 0 came up normally with no Disk Utility configuration necessary. The order of the disks, as in the “USB 3.0 Hub RAID” configuration, does not matter.
  • The quick start guide does not mention the need to install a driver for the MacBook Pro running OS X in order to see the “Promise Pegasus J4”, but the drivers are required. Thanks to Dong Ngo’s review on CNet for the link:


The “Promise Pegasus J4” is more cumbersome to store in a laptop bag than four, bus powered, USB 3.0 drives and a hub, but easier to operate with only one AC power cored, no wall wart and a Thunderbolt cable. The “Promise Pegasus J4” fits in the “Level8 15inch Pro SuperSleeve” with the MacBook Pro 15 inch Retinal Display, although the bag looks overstuffed. By propping the laptop on the “Promise Pegasus J4”, or placing the “Promise Pegasus J4” on its side in the seat along side of you, or placing the “Promise Pegasus J4” on your lap with the computer on the tray it is possible to use on an airplane assuming A/C power is provided.


The “Promise Pegasus J4” shows marginal improvement over the “USB 3.0 Hub RAID” using 2 hubs and significant improvement over 1 hub:

Comparing the Promise Pegasus J4 with the "USB 3.0 Hub RAID"

Comparing the Promise Pegasus J4 with the “USB 3.0 Hub RAID”

All the data that is fit to print on the Promise Pegasus J4

All the data that is fit to print on the Promise Pegasus J4


The empty box is $369, about the cost of the four 1TB, bus powered, USB 3.0, 7200rpm drives. This is currently the best price point for a large capacity (4TB), high speed (over 400MBytes/sec), “portable” (fits in laptop bag, can be used in an airplane) solution.


The “Promise Pegasus J4” gives you a reason to use the Thunderbolt port on your laptop and you might need the USB ports for something else, like your backup disk array, which does not need to be as fast.