Resilient to power loss
YAFFS’ journalling approach is designed for systems that may lose power at any moment. After a sudden power cut or reset, the file system recovers to a consistent state without complex manual intervention.
Why YAFFS
Reliability and consistency, by design
YAFFS exists to make flash storage boringly predictable. It is engineered for raw NAND and NOR flash in embedded systems where reliability matters more than anything else.
Engineered for raw flash
Many file systems were designed for spinning disks and later adapted to flash. YAFFS went the other way: it starts with the realities of flash and builds upwards.
- Handles bad blocks and wear as first‑class concerns.
- Optimised for page and block sizes typical of NAND/NOR devices.
- Does not depend on a separate flash translation layer.
- Designed to run on Linux, RTOSs or directly on bare hardware.
Designed for predictable behaviour
YAFFS is not chasing benchmark headlines – it is tuned for stability and consistency over years of operation. That means fewer surprises and easier reasoning about your system’s behaviour in the field.
Consistent over the product lifetime
Behaviour remains stable as the device ages, blocks wear and workloads vary. That consistency helps you avoid rare “once in a million boots” issues that are hard to reproduce and even harder to ship around.
Proven in the field
YAFFS has run in shipped products since 2002 – in networking equipment, industrial controllers, sewing machines, and even satellites. That history represents years of real‑world edge cases already handled.
Fit
When YAFFS is a good choice
Choose YAFFS when
- Your design uses raw NAND or NOR flash, not just SD cards or SSDs.
- You care more about reliability and predictability than chasing maximum throughput.
- You expect irregular or harsh power conditions (battery removal, brown‑outs, noisy supplies).
- Your product lifetime is measured in years and you want storage to keep up.
- You need a small, understandable code base with expert support behind it.
When another approach may be better
If you only use managed storage (for example eMMC, SSDs or SD cards) and never touch raw flash, you may be better served by the file systems shipped with your operating system and the FTL inside those devices.
For mixed or complex environments, the YAFFS team can help you decide what combination of hardware and software gives you the reliability and consistency you need.
Learn more about design trade‑offs
Choosing the right flash file system involves trade‑offs between reliability, performance, complexity and licensing. We have captured some of those considerations in more depth in our design notes and papers.
- Considerations in Choosing a Flash File System (PDF) A deeper look at the issues you should consider when selecting a flash file system.
If you would like to discuss your specific design, our consulting and support services are available to help you reach a decision with eyes open.
Talk to the YAFFS team