Comparison of SD Card Performance on a Raspberry Pi 4 @Raspberry_Pi #PiDay #RaspberryPi
via Jeff Geerling
One thing that is almost universally true (at least as of 2019) is that the most common system boot device is a microSD card. SD cards in general have performance characteristics that pale in comparison to faster devices, like NVMe SSDs, eMMC, and XQD or CFexpress.
On top of that, the performance metrics used in microSD marketing are usually targeted only at the major market for these tiny memory chips: those who record video and stills on them, and only ever really care about massive file read/write performance.
For general purpose computing—which is what SBCs like the Raspberry Pi do—random I/O performance is much more important. And here is where most of even the most expensive microSD cards fall incredibly short.
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