If a switch, router, or firewall has been running continuously for 10–15 years, how likely is it that its internal flash storage will still be healthy after a reboot and able to load the operating system into RAM? What kind of lifespan should I expect from the flash in these devices, and does the manufacturer matter significantly, or is reliability mainly determined by the specific flash technology, component quality, and how often the storage is written?
4 Answers
In practice, the hardware may keep running long after the software is unsupported or no longer safe to expose to a network. I would plan replacement based on vendor support, security updates, spare-part availability, and the device’s role rather than assuming the flash will last forever. Some older units run for 15–17 years, while a brand-new unit can still fail within months due to ordinary component defects.
Boot firmware may also be stored partly in ROM or other protected storage, depending on the design, which makes the basic startup code quite resilient. The main risk is usually not a simple age-based expiration of flash, but accumulated write wear, power-related damage, filesystem corruption, or an unrelated hardware failure.
The component type and build quality matter more than the brand name alone. SLC, MLC, and TLC flash have different endurance characteristics, and embedded networking hardware often uses relatively reliable parts with conservative workloads. Even so, individual failures can happen early, while other devices continue working for well over a decade.
Flash generally tolerates read operations very well; repeated writes are what wear it out. Network appliances usually read their operating system from flash and keep active data, logs, and temporary files in RAM or on another storage device, so the flash may see relatively few write cycles. There is no guaranteed lifespan, but 10–15 years of service does not automatically mean the boot flash will fail.

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