Hands-On with the Kobol Helios64, a Five-Bay Armbian-Based RK3399-Powered Open-Spec NAS System

After a pandemic-related manufacturing delay and a specification downgrade, the Helios64 — Kobol's follow-up to the Helios4, an open-spec Arm-based single-board computer designed for those looking to roll their own network attached storage (NAS) solutions — is finally here, but has it been worth the wait?

Kobol's original Helios4 launched four years ago via Kickstarter, crowdfunding for an open-specification NAS system housed in a clever laser-cut acrylic chassis. The Helios64 is a considerable upgrade on all fronts, including in its custom-designed five-bay metal housing with hot-swap drive sleds, but the route to production has not been smooth: Kobol announced a delay earlier this year, blaming the impact of the SARS-CoV-2 pandemic, and in doing so confirmed that the planned Rockchip RK3399K system-on-chip was to be swapped out for the somewhat slower RK3399 — seeing a drop in clock speed from 2GHz to 1.8GHz for the two Arm Cortex-A72 cores.

The other specifications, thankfully, have remained intact: Five 6Gb/s SATA ports, one shared with an M.2 SATA slot on the main board; 4GB of non-ECC RAM; two pulse-width modulation (PWM) fan headers for bundled 80mm cooling fans; two Ethernet ports, one gigabit and the other 2.5-gig-E; an external power supply; 16GB of on-board eMMC storage; and an optional battery-backed internal uninterruptible power supply (UPS) system for increased availability and protection from data corruption during power loss.

Solid, But Flawed, Hardware

The Helios64 chassis takes up the majority of the packaging, for obvious reasons. Supplied as a partially-assembled kit, buyers have an hour or two of assembly to look forward to: Putting the case together is relatively straightforward though care needs to be taken that stickers for the rear panel and front panel are applied correctly, and the wiring loom which stands in for a SATA backplane PCB is time-consuming to assemble.

Sadly, it's during assembly that the first few issues make their presence known. The quality of the finish is far from perfect, with the internal drive rails showing signs of rust in our review unit and sharp edges working to shave curls of plastic off the brightly-colored drive rails as they're inserted. While our assembly went smoothly, users of the official support forum have reported problems ranging from faulty wiring looms and fans to a short in the front panel which lights up all the warning LEDs regardless of system status.

That's not to say there aren't positives to be found in the design. The case is extremely solid and visually attractive, while the front panel's magnetic connection feels like magic as you attach and remove it to gain access to the five hot-swap bays. The blue status LEDs, though, are blindingly bright — something Kobol has confirmed it plans to address in future manufacturing runs.

There are two more serious design flaws to add to the mix, however. The first is the most serious: The much-vaunted 2.5-gig-Ethernet port is capable of crashing the system if run with hardware offload enabled, and comes with a nasty mistake in the schematic whereby the ground connection isn't properly made — meaning a dramatic drop in performance when connected to a standard gigabit Ethernet switch. There's a fix, but it's not for the faint-hearted: Solder a bodge wire in place, a process which Kobol confirms will mean goodbye to the board's warranty. The second flaw, meanwhile, prevents the use of the bundled USB cable unless and until you shave its plastic plug housing down a few millimetres to allow it to make a proper connection to the Helios64's rear-facing USB Type-C port.

Powered by Armbian

Rather than take the all-too-common approach chosen by Arm board manufacturers of building a custom board support package, releasing a single port of a usually-outdated Linux distribution, and then abandoning its users, Kobol has partnered with the Armbian project. The result is that there are two operating systems available for the Helios64: One is based on Canonical's Ubuntu Linux, and the other based on its upstream Debian Linux.

Like many single-board computers, the Helios64 is booted from a microSD slot at the rear — but only for initial installation. Users have a choice of continuing to use the microSD slot, switching to the 16GB on-board eMMC storage, or loading just UBOOT to the eMMC and booting from a hard drive, SSD in the M.2 slot, or a USB device. Those looking to use the M.2 slot need to bear in mind, though, that it disables the first of the five SATA hot-swap drive bays.

Software support has been a thorn in Kobol's side since it finally shipped the hardware — and this review has itself been delayed to account for a selection of bug fixes. At the time of writing, the Armbian builds for the Helios64 were still marked as a work in progress with "no end user support" — though Kobol itself runs a "club" on the Armbian forums and chimes in with advice and roadmap updates. While our installation of Armbian Focal has proven stable, others have reported of frequent crashes even while running the latest release — and that's not even accounting for the occasional regression, such as the accidental exclusion of the driver for the 2.5-gig-E port in the most recent release which saw the port disappear from the host on reboot post-updating.

It's taken Kobol a while to offer promised features, too — and some, like hardware offload on the 2.5-gig-E port, are still not available at the time of writing. Support for the optional UPS, which powers the system in the event of mains loss, is still rudimentary: A script exists which monitors for mains loss and shuts the system down after ten minutes, but this seems extremely conservative given our testing with a two-drive-plus-M.2-SSD setup saw the battery keep the system running for an hour and 39 minutes. A community member has written an alternative script, capable of tracking the actual charge of the battery, but there's no word on this being adopted as the official tool.

There's one more issue to flag, too: With six cores, two high-performance Cortex-A72 cores and four lower-power Cortex-A53 cores, the temptation is there to throw virtualized workloads at the system; the processor, however, is vulnerable to Spectre v2 and speculative store bypass attacks with no mitigations planned — meaning it's possible, though challenging, for virtual machines to attack the host machine.

Impressive Performance

To focus on the Helios64's negative points is to miss out on what makes it special. It's an attractive and compact design in a market which is flooded by bulky black boxes, and the open-spec approach combined with its use of an open source operating system will appeal to those who like to tinker with their systems rather than run off-the-shelf proprietary devices.

Performance is good, too, easily equalling other RK3399-based devices like the Orange Pi 4B while outstripping them in certain memory-hungry workloads like file compression thanks to a higher-than-usual memory bandwidth. A clever Armbian-specific background process helps here, too, monitoring for compute-heavy threads and moving them to the two high-performance Cortex-A72 cores — meaning you should never find your hungriest processes running on the slower Cortex-A53 cores unless the two faster cores are already busy with higher-priority tasks.

To get the best performance, though, you'll find yourself sacrificing a drive bay to fill the M.2 slot with an SSD: The review unit was able to sustain 23.9MB/s read and 16.9MB/s write to a microSD card and a rather more impressive 186MB/s read and 56.2MB/s write to the on-board eMMC, both of which failed to get anywhere near the 554MB/s read and 514MB/s write available at the cost of the first hot-swap drive bay.

The Helios64 is pretty friendly when it comes to energy usage: In the tested configuration of two 6TB SATA hard drives and a 240GB M.2 SSD boot drive, the Helios64 drew 15.5W — measured at the wall — while idle and 28W with the CPU fully loaded. If the internal UPS battery needs charging, the idle figure rises to 27.5W for the duration of the charge cycle.

Conclusion

The Helios64 is an impressive second launch from Kobol, and one which is leaps and bounds ahead of its predecessor — but the company still has some way to go with the project. Before it opens orders for the next manufacturing run, it desperately needs to address the core design flaws: The faulty 2.5-gig-Ethernet port, the too-tight-and-sharp drive mounts which shave plastic off the rails; the reliability issues in the SATA backplane loom; the need to take a sharp knife to the USB cable to use the Type-C port at the rear; and the blinding, and sometimes shorted-out, front-panel status LEDs.

While those improvements won't placate those whose pre-orders have already been delivered, improvements on the software side should help. Kobol particularly needs to lock down its Armbian port, fixing the reliability issues, guaranteeing stability, and ensuring that future updates don't come with unwanted side effects like the accidental loss of the driver for the 2.5-gig-Ethernet port in the latest release. The still-missing features, like hardware offload and true charge monitoring for the UPS, should follow.

With these issues taken care of, the Helios64 would be easy to recommend. It's smart, stylish, and offers a great balance of performance and power draw. It's also inherently multifunctional: As well as operating as a headless NAS, the Helios64 can be used a USB Direct Attached Storage (DAS) system or as a desktop system with graphical output via its USB Type-C port — though both of these features are still awaiting software support for full functionality.

Kobol has confirmed it will be taking orders for the second batch of Helios64 systems at $295 on its official website, including the board, case, external power supply, and UPS; the company has also suggested it will be selling the Helios64 boards uncased, and the bundle without UPS, but has not yet confirmed batch two pricing for these options.