OWC ThunderBay IV review: a solid and versatile desktop storage solution

OWC's ThunderBay IV Locked
Michael Homnick

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At a Glance
  • OWC ThunderBay IV (12TB)

Multi-bay storage enclosures are versatile; you can reconfigure them for speed or redundancy depending on your needs. The ThunderBay IV from OWC has four drives that can be swapped easily with the aid of a screwdriver. You can configure the disks independently or as a RAID with the help of Disk Utility. The ThunderBay IV's simple design and consistent performance make it an attractive desktop storage device.

OWC's ThunderBay IV Michael Homnick

Drives slide out the enclosure easily, but you need a screwdriver to get them out of the caddies.

While the drive case is black like the late 2013 Mac Pro, the perforated metal front panel is reminiscent of legacy Mac Pros. The front panel has to be unlocked with a key to access the individual drives, and the key acts as a handle for pulling the front panel off the drive. Status lights for power and drive activity are visible through the front panel. A large fan in the back of the drive pulls air through the perforated front panel and expels it out the rear. Below the fan are two Thunderbolt ports for daisy chaining, a Kensington lock slot, and power switch.

ThunderBay IV Drive Adapter Brackets Michael Homnick

You need adapter brackets to use 2.5-inch drives in the ThunderBay IV.

The drives (our unit came with 3.5-inch Toshiba DT01ACA300 mechanisms) are mounted on caddies with four screws, so you need a screwdriver to swap out the drives. In order to use any 2.5-inch drives in the 3.5-inch brackets you need to use a NewerTech AdaptaDrive converter bracket. I tried using a standard 2.5-inch to 3.5-inch adapter that comes with most SSDs, but the SATA connections on both the adapter and the ThunderBay IV didn't quite match up. Four of these adapters cost upwards of $60 total, something to keep in mind if you're looking to buy the ThunderBay IV unpopulated, or want to mix and match drive sizes.

Write File
  • OWC ThunderBay IV749
  • CalDigit T3564
  • LaCie 5big784
  • Promise Pegasus R6789
Read File
  • OWC ThunderBay IV744
  • CalDigit T3567
  • LaCie 5big672
  • Promise Pegasus R6681

Drives tested as RAID 0.
Results are in MBps; larger numbers/longer bars are better.

With four drives, you can take your pick of software RAID configurations: 0, 1, 10, or JBOD. As a RAID 0 setup, the ThunderBay IV performs quite nicely. It can keep up with more expensive multi-bay drives like Promise's Pegasus R6 and LaCie's 5big Thunderbolt Series.

Write Folder
  • OWC ThunderBay IV514
  • CalDigit T3458
  • LaCie 5big483
  • Promise Pegasus R6519
Read Folder
  • OWC ThunderBay IV468
  • CalDigit T3521
  • LaCie 5big524
  • Promise Pegasus R6407

Drives tested as RAID 0.
Results are in MBps; larger numbers/longer bars are better.

RAID 10 gives you data redundancy with a speed boost by creating a RAID 0 from two RAID 1 sets. We tested the drive under a RAID 10, and the speeds were about twice as fast as if the disks were managed independently. Keep in mind that, much like a RAID 1 configuration, RAID 10 limits you to half your total storage capacity.

OWC's ThunderBay IV from behind Michael Homnick

A large fan in the back cools the drive and keeps noise to a minimum.

Bottom line

OWC's ThunderBay IV delivers impressive performance at a much lower price point than much of the competition. This makes it a great choice for professionals who want large storage capacities without having to forfeit speed.

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At a Glance
  • OWC's ThunderBay IV performs quite well and its price-per-gb is competitively low.


    • Two Thunderbolt ports for daisy chaining


    • Additional adapter required for 2.5-inch drives
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