Fast and silent hybrid RAID system: CalDigit T4

CalDigit is a supplier of storage solutions for creative professionals, including photographers, movie makers and video producers. The T4 is their hybrid Thunderbolt 2 RAID-capable storage solution. T4’s have a tightly fitting aluminium cast enclosure aimed at silent operation and good thermal management. They have four lockable removable drives that carry a three-year warranty. The unit itself carries a five-year warranty.

CalDigit T4 box shot

CalDigit sent me a T4, but before they actually sent one out to me, the representative asked me what I was testing it for and what with. Was I going to test the units to backup with Time Machine, or was I going to edit videoclips right off the T4? Based on my answers, they sent me a T4/8TB. They tested the drives inside the unit — Toshiba DT10ACA200 drives — before shipping. It was a type of customer care you rarely encounter these days, one that instigates trust.

T4 RAID configurations and performance

The T4 is an SSD or HDD based hybrid RAID solution, factory configured for macOS. Support for SSDs isn’t all that common with RAID systems. It allows CalDigit to ship a T4/4TB that has throughput speeds of up to 1370MB/sec in RAID 0. Contrary to some other vendors selling RAID storage for the desktop video editing market, CalDigit’s T4 is made of die-cast aluminium, not of plastic or a wrapped metal sheet. Die-cast aluminium has superior heat dissipation characteristics.

CalDigit T4 RAID solution with drive keys
CalDigit T4 RAID

To configure RAID modes, you use a menu applet. The applet has a tab with system information including per-disk operating temperature, serial number, SMART status, etc. Another tab lets you set the unit to RAID 0, 1, 5 or JBOD. Unique about the T4 is that you can set up two different RAID 0 or RAID 1 configurations — each using two drives. You can also set up a RAID 5 with all four. Finally, you can set up one RAID 0 or 1 configuration and have the two other disks function as independent drives. Other applet features include notification preferences and a benchmarking tool that seems to be based on the AJA speed test utility.

As I said earlier, the die-cast aluminium enclosure of the T4 dissipates heat efficiently. It has cooling ribs on the sides and a ventilator in the back. The drives in my unit never ran warmer than 37°C with an ambient room temperature of 25°C. That’s in stark contrast with the 52°C my iMac’s internal disk regularly reaches.

I was wary of the ventilator’s sound levels, though. The CalDigit T4 is extremely compact and has what seems to be a plain fan, so it could generate a lot of noise. However, although it’s not completely silent, the fan noise is low enough even after an hour of editing not to interfere with normal audio levels too much. To give you an idea: before turning the unit on, the sound level in my room reached 36dBA. After turning it one, it rose to 38-39dBA.

Blackmagic Design disk speed with 2 GB file
Blackmagic Design disk speed utility test with 2 GB file.

The quality of build of the T4 is undisputed, but its speed is downright exemplary. Before copying files to the T4, I tested its performance with both Blackmagic Design’s and AJA’s speed utilities. CalDigit claims a T4 with hard disk drives can achieve a maximum throughput of 750MB/sec in RAID 0 and 550MB/sec in its default RAID 5 configuration. It’s useful to know that performance claims usually list the highest figure, which is always the device’s read speed. Furthermore, CalDigit will undoubtedly have tested with a Thunderbolt 2 capable Mac.

AJA disk speed test with 2GB file.
AJA disk speed test with 2GB file and 4K video frame size set.

My own iMac is equipped with first generation Thunderbolt only, so I expected lower figures overall. I was in for a nice surprise. The file read figures that I achieved were almost identical to CalDigit’s claim as you can see from the screenshots. More importantly, however, is that the equally important write speeds are pretty impressive as well — even on my Mac.

The best news is that RAID 5 writing speeds are close to RAID 0’s. In practice you only lose about 100MB/sec read performance but nought in write mode. That’s not all, I found. I ran the speed test with Blackmagic Design’s utility again after I had copied 1.5TB worth of files to the T4 in RAID 5.

Blackmagic Design disk speed with 1.5TB loaded onto T4.
Blackmagic Design disk speed with 1.5TB loaded onto T4.

With other RAID drives I have always seen a drop in performance once there are files on the system. Not so with the T4 — at least not worth mentioning.

CalDigit T4’s in a practical environment

Speed tests tell you how fast a system is, but it doesn’t tell you how fast it feels. So, I launched Final Cut Pro X and took to colour grading a timeline with Color Finale, adding a tracked text with TrackX and further slowing down things by adding a Yanobox Nodes 2 compositing element.

Rendering was snappy, tracking was quite fast and the Yanobox Nodes 2 animations didn’t drive me crazy by taking forever. The sound levels were definitely not high enough to be frustrating but when the audio became somewhat quieter, I did grab for my headphones and stopped listening to the monitors. I can’t set the volume on them high enough anyway in order not to disturb the neighbours.

My iMac has passed its “Best before” expiration date for video-editing for some time now, but by running macOS off an SSD two years ago, I managed to extend its non-frustrating lifespan with a couple of years. The T4 makes it feel snappy all over again.

The T4/8TB costs €1338.99. You can buy a T4 with 4TB, 8TB, 12TB, 16TB and 20TB of RAID 0 hard disk space. The SSD version costs €3659.99 and gives you 4TB of RAID 0 space to work with.

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