The weak spot of SBCs

Card Game

An omnipresent characteristic of current single-board computers (SBCs) is the use of SD cards to provide mass storage functionality, either for system boot or data storage purposes. Unfortunately, SD cards are not particularly reliable devices, and their intended purpose is storing pictures as they are captured by a digital camera – perhaps the most sequential storage access task that could possibly be imagined. Booting an operating system (OS) exhibits a much more randomized access pattern, as I have previously discussed in the case of marginally better USB storage "sticks" [1], presenting the device with challenges to the processing of allocations and deletions at sustained rates.

That article examined the performance difference between USB storage with high-end brand names and more generic devices and compared the resulting write performance. Today, I am examining the limits of SD performance in a specific SBC instead: the all-in-one Raspberry Pi 400. (Figure 1). The Raspberry Pi 400 [2] is a custom board redesign (for cooling reasons) of the Raspberry Pi 4 in the once popular "computer in a keyboard" form factor of days past. Board layout aside, it can be thought of as a Raspberry Pi 4 SBC with 4GB of RAM, WiFi access, and some additional layout changes to expose the GPIO connector at the back of the keyboard.

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