Opto 22 keeps its industrial controllers power-fail safe with Tuxera NitroFS

An open Linux controller for the plant floor

Opto 22 designs and builds industrial automation hardware and software, with a long history in solid-state relays and Ethernet-based I/O. Its devices run in energy, manufacturing, and critical infrastructure sites around the world, where customers expect a controller to stay in service for many years. With groov EPIC, which Opto 22 describes as the world’s first edge-programmable industrial controller, the company put an open Linux operating system at the center of the product, so customers can run their own software on it and adapt the Linux environment to their applications.

Why power loss is a file system problem

Linux-based devices carry a known weakness in industrial settings. If power drops or a unit is switched off while it is writing data, the file system can be left in an inconsistent state, and the device may not boot cleanly the next time it starts. On a plant floor, power cuts and abrupt shutdowns are part of normal operation, and industrial controllers lose data after power interruptions for reasons that are well understood. Opto 22 set out to remove that risk from groov EPIC before it shipped.

Ken Johnson, VP of Engineering, Opto 22: “These products must work flawlessly in industrial environments whether the power is lost or switched off abruptly. This was a major challenge for critical industrial operations.”

Months of testing, and no file system passed

The engineering team spent months testing widely available file systems, including BTRFS, OverlayFS, and its own modifications to EXT4. Each candidate faced 20,000 random power interruptions, many of them timed to hit the boot process, the window where a device is most exposed to corruption.

Ken Johnson: “None of the file systems passed our internal tests. Even those marketed with resilience features failed to recover consistently.”

Tuxera NitroFS changed the results from the first round, with initial power-fail tests producing clean boots and no file system corruption. Opto 22 also weighed building the same level of power-fail safety itself and concluded it would be a multi-year project.

Ken Johnson: “If we had to develop this level of resilience ourselves, it would take at least three man-years. NitroFS gave us the confidence to let customers tweak our Linux software and run their own implementation without any risk.”

From groov EPIC to groov RIO

NitroFS shipped first in groov EPIC. A few years later, Opto 22 used the same file system in groov RIO, its edge I/O controller. Both products went through extensive testing that included hundreds of thousands of power-fail events, and the controllers rebooted cleanly throughout. For the engineering team, that meant less time on low-level fault handling and more on application features, and it let the company keep building its industrial products on Linux.

Ken Johnson: “This level of resilience to power outages is still one of our key differentiators. Our customers want robust and stable devices they can trust for decades.”

NitroFS in the next generation of Opto 22 products

Opto 22 plans to keep NitroFS as a foundational component in its upcoming platforms, and its engineers continue to develop new products on it.

Ken Johnson: “After years of great experience, we continue to keep the Tuxera file system, NitroFS, as an integral component in our next-gen industrial innovations.”