The old Mac Pro, which was around for more than five years, had four internal 3.5-inch hard drive bays. This was great, because multiple drives could be easily installed for RAID, backup, or scratch disk purposes. I have a 2008-era Mac Pro hidden in a closet as a whole home media server, and it has four 3 GB drives inside.

However, for the new Mac Pro, launched late last year, Apple skipped all the internal upgradability in favor of a sleek new design and ultra high speed SSD storage. Instead, Apple’s engineers installed six Thunderbolt 2 ports capable of moving data bidirectionally at 20 Gbps.

Thunderbolt 2 devices have been somewhat slow to hit the market (though Thunderbolt 1 devices are decently plentiful) — but now, Other World Computing has released a new 4-bay Thunderbolt 2 external drive enclosure that should meet the storage needs of many pro- and prosumer-level users.

The ThunderBay 4 (not to be confused with the ThunderBay IV, which only supports Thunderbolt 1) has a pair of Thunderbolt 2 ports for daisy chaining and holds up to four 3.5″ hard drives or SSD modules for more extreme performance.

It’s available in two versions, one with SoftRAID 5.0 built in and one that’s effectively a JBOD (just a bunch of disks) system like the old Mac Pro. SoftRAID 5.0 is a software RAID setup that allows users to create a RAID 5 array, striping data across multiple drives for increased speed — so, if a single drive dies, no data is lost. SoftRAID also offers drive health monitoring and email notification if there are any issues.

My 12 TB tester unit had four 3 TB hard drives set up in a RAID 5 array, giving 9 GB of actual storage. Write speeds averaged around 183 MB/s, with read speeds of near 550 MB/s (Figure A). These aren’t quite comparable to the internal SSD storage on modern Macs, but for many users, it will be more than fast enough for storage of large files or as a scratch disk for applications like Adobe Premiere or Final Cut Pro X.

Figure A

Disk Speed Test.

The drives are held inside a minimalist black case with internal fan for cooling — it was relatively quiet but slightly louder than my iMac, and significantly quieter than my old Mac Pro. There’s an honesty lock on the front to prevent the accidental removal of drives, but given the size of the box itself, it would be easy for a thief to simply pick up. A single Thunderbolt cable is included in the box.

Pricing varies, depending on the number of hard drives and whether the SoftRAID 5.0 software is included. You can purchase the ThunderBay 4 from Other World Computing in these configurations:

  • The ThunderBay 4 without SoftRAID 5.0
    • No included hard drives: $499.99
    • 4 x 1 TB: $729.99
    • 4 x 2 TB: $879.99
    • 4 x 3 TB: $997.99
    • 4 x 4 TB: $1349.99
    • 4 x 5 TB: $1729.99
  • The ThunderBay 4 with SoftRAID 5.0 built in:
    • 4 x 1 TB: $880
    • 4 x 2 TB: $1000
    • 4 x 3 TB: $1130
    • 4 x 4 TB: $1480
    • 4 x 5 TB: $1850

For $500, Mac Pro owners who want to upgrade can seamlessly move their hard drives from their old machine into the ThunderBay 4. Performance and pricing are both excellent, which makes the ThunderBay 4 a great solution for any Mac owner looking to add external storage to any modern Mac.

What’s your preferred method of storage for your Mac? Does the ThunderBay 4 have what it takes to justify the cost? Share your thoughts in the discussion thread below.

Updated Friday, June 27, 2014: After this article’s original publication, Other World Computing contacted me with concerns about what they thought were slow write speeds in my testing of the ThunderBay 4. It turns out that while the SoftRAID 5.0-equipped machine comes from the factory set up as a RAID 5 array, a dramatic increase in speeds is seen once the included SoftRAID 5.0 software is installed.

In a second test of the unit, I installed the software on my Mavericks-equipped iMac (but made no other changes), and write speeds increased from 185MB/s to 469MB/s on the BlackMagic speed test, with a small increase on read speeds from 550MB/s to 572MB/s (see Figure B).

This is a dramatic difference and I’ve recommended that Other World Computing make it clear to to buyers that installing the SoftRAID software is essential to getting the highest levels of performance out of the machine. In light of these changes, the ThunderBay 4 is an even better deal for users looking for fast external storage.