Opinions of the Pegasus J4

Discussion in 'Mac Accessories' started by maflynn, Apr 21, 2014.

  1. maflynn Moderator


    Staff Member

    May 3, 2009
    Its a lower priced thunderbolt external drive unit that holds 4 2.5" drives.

    The Drobo mini is probably its main competitor.

    From the reviews I've read, it appears to use OSX' RAID feature and not any hardware raid since you need to set it up in the Disk Utility App. Is that true, or am I misunderstanding things?

    How's the performance of the J4 via thunderbolt?

    At 369 and up, its a bit pricey, what external Thunderbolt drives would be better (and faster) but not terribly more expensive?
  2. hfg macrumors 68040


    Dec 1, 2006
    Cedar Rapids, IA. USA
    I am using a Pegasus J4 with my 2012 iMac and I like it. It currently is configured with 4ea. HGST 1TB 7200rpm hard disks set up as a pair of 2-disk RAID-0 arrays. Since it appears to the computer as JBOD, you use DiskUtility to configure it as you wish in RAID-0, RAID-1, RAID-10, Concatenate, or simply leave it as individual disks. There is no hardware RAID controller in the J4. Note that it requires a OS X driver, thus the J4 cannot be used as a boot device (not a problem for me as I boot from the iMac SSD and use the J4 for data).

    I did some BlackMagicDesign DiskSpeedTest runs when I got it...

    Promise Pegasus J4 Results:
    config ....... Write / Read MB/s
    1 disk ....... 115 / 129
    2 disk ....... 250 / 258 RAID-0
    3 disk ....... 345 / 375 RAID-0
    4 disk ....... 501 / 507 RAID-0

    545 / 856 Pegasus J4 RAID-0 with 2x 840Pro 256GB SSD

    There has been a report here that the power supply of the J4 is unable to power 4ea 1TB SSDs Samsung 840 EVO. I don't know if that was an isolated incident or a design issue. Promise Technology does not list any large SSDs on their drive compatibility list.


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