CalDigit T3: Lightning-fast Thunderbolt RAID

CalDigit T3 RAID Array

Back at the end of 2012 I purchased a pretty well-equipped iMac and naively believed that the 1 TB Fusion Drive was going to be all the storage I would need for a long time. Less than 18 months and a lot of video editing later, I'm watching as the last 200 GB dwindle away. That's why it's great that products like the CalDigit T3 exist. It's a Thunderbolt RAID box with space for three hard drives or SSDs set up in either RAID 0 (striped set) or RAID 1 (mirrored) configuration. Pop three 4 TB HDDs into this sleek box and you can have a 12 TB striped set or 4 TB of mirrored storage. You can also set up your T3 as JBOD (just a bunch of disks) if you wish.


  • Price: From US$449 (three 1 TB HDD) to $2799 (three 960 GB SSD). Available in hybrid (SSD + HDD) configurations as well. Price as tested: $749

  • Dimensions: 4.5" x 5.3" x 9.5" (116 x 135 x 242 mm)

  • Weight: 6.1 lb/2.76 kg (3 SSD), 9.98 lb/4.53 kg (3 HDD)

  • Ports: 2 Thunderbolt ports

  • Power: Proprietary power supply adapter, 100-240V, 2.0A, 50-60 Hz input; 12V, 7.5A DC output

  • Material: Aluminum

  • Enclosure Specifics: Not rack-mounted, the CalDigit T3 is a self-contained unit

Design Highlights

CalDigit makes some really fine products, and the T3 is no exception. I was impressed with the CalDigit Thunderbolt Station earlier this year, a Thunderbolt-based expansion dock that offers a variety of ports in a compact size. The T3, of course, is really something you'll want to keep in a desktop environment due to the sheer weight of the device.

The three drives -- you can mix or match hard disk drives or SSDs -- come in proprietary drive modules that must be purchased from the company. While I'm not a fan of proprietary modules, I have to commend CalDigit for making these affordable. A 1 TB HDD module in an archive box runs $129, while a 4 TB module is $339. There's a single SSD module capacity available at 960 GB for $799.

Made of aluminum with special keys used to lock the drive modules in place, the T3 is one of the most solid pieces of equipment I've had the pleasure to use in quite a while. CalDigit's other products also have that solid, well-built feel and look to them, and it's great to see a manufacturer that takes the time and effort to create products that look like they'll last for years.


Setup of the CalDigit T3 is a piece of cake: Just plug the Thunderbolt cable into a port on your Mac and then into one of the two Thunderbolt ports on the back of the device. Plug in the AC Adapter, and plug the appropriate end into the T3. Turn on the T3. That's it. You can choose to set up the drive in RAID 0 or RAID 1 configurations using OS X's Disk Utility.

For the purposes of testing external drives and RAID arrays, we traditionally use the Intech SpeedTools QuickBench 4.0 app to run multiple cycles of read/write tests. The T3 was directly connected to a MacBook Pro with Retina display using an Apple Thunderbolt cable.

To ensure accuracy in testing, I performed a 100-cycle complete test. This subjects the drive to sequential and random read and write tests with file sizes from 4K to 100 MB, then graphically or textually displays that information to show the "sweet spots" for a specific drive or array. For example, if your work involves shuffling around a lot of very large files, you'll probably want a drive that has peak read/write speeds for files around your average file size. Here are the test results for a RAID 0 stripe set, compared with a Drobo 5D also using a Thunderbolt connection:

  • Sequential Read: 313.917 MB/Sec (140.504 MB/Sec for Drobo 5D connected via Thunderbolt)

  • Sequential Write: 279.731 MB/Sec (93.245 MB/Sec for Drobo 5D connected via Thunderbolt)

  • Random Read: 69.402 MB/Sec (116.435 MB/Sec for Drobo 5D connected via Thunderbolt)

  • Random Write: 62.263 MB/Sec (70.410 MB/Sec for Drobo 5D connected via Thunderbolt)

  • Large Read: 538.599 MB/Sec (341.327 MB/Sec for Drobo 5D connected via Thunderbolt)

  • Large Write: 763.516 MB/Sec (282.060 MB/Sec for Drobo 5D connected via Thunderbolt)

  • Extended Read: 552.096 MB/Sec (255.953 MB/Sec for Drobo 5D connected via Thunderbolt)

  • Extended Write: 553.392 MB/Sec (262.864 MB/Sec for Drobo 5D connected via Thunderbolt)

In just about every benchmark, the CalDigit T3 blasted by the speeds provided by a five-port competitor, the Drobo 5D. The exception to the rule was in random read/write tests performed with smaller file sizes (4KB to 1024 KB), where slow throughput on the very small files really slowed down the results.

Get into large files, though, and it's tough to beat the T3. These files are in the 2 - 10 MB size range, and the T3 chewed 'em up and spit them out at high speed. The write throughput of 763.516 MB/Sec is incredible -- this would be a perfect drive to use for capturing video. Extended files in the 20 to 100 MB range were also written and read quickly at over twice the speed of the Drobo 5D.

For RAID 1 (mirroring), the results were not as fast as those for RAID 0 -- but that's expected. While a stripe set basically writes your data once across the three drives in the T3 array, the mirrored set is writing three copies of the data. Without a comparison, here are the throughput numbers for the mirrored T3:

  • Sequential Read: 132.220 MB/Sec

  • Sequential Write: 128.190 MB/Sec

  • Random Read: 20.684 MB/Sec

  • Random Write: 22.327 MB/Sec

  • Large Read: 291.590 MB/Sec

  • Large Write: 181.604 MB/Sec

  • Extended Read: 330.083 MB/Sec

  • Extended Write: 165.950 MB/Sec

One final environmental note: the T3 is really quiet in operation. Although there is some fan noise, it's truly white noise that doesn't get on your nerves and there is no drive "clicking" to be heard at all. This would be a really good unit to use even in a quiet office.


CalDigit's T3 is the fastest Thunderbolt RAID array we've had the opportunity to test so far. If you have a need for large, fast storage or multiple mirrors of your data, this is the device to look at. You'll be able to store your data on an external drive without it becoming a bottleneck to throughput, thanks to the speed of the Thunderbolt connection. Ease of setup, solid design, and exceptional speed make the CalDigit T3 a top choice for anyone who needs fast and reliable storage.

Rating: 4 stars out of 4 stars possible