I have some fast microSD cards and some USB 3 microSD card adaptors. The card speed should be similar in a USB 3 adaptor when compared to the Pi 5 microSD card slot. USB overheads are only about 10% max.
I tested several combinations. One adaptor failed to the point where the Pi 5 put up the boot diagnostic screen. Two adaptors reached the Pi first screen then locked up without completing the boot. Only one adaptor booted all the way. Some of the failed adaptors worked in a Pi 4.
In the Pi 4, they all worked for data access. I remember one not booting.
The one adaptor booting in the Pi 5 produced speed tests about half the speed of the Pi 5 microSD card slot. The speed difference is consistent across reads and writes, across the three measurements in the Pi Diagnostics, and across another speed test.
The cards are A1 so the difference is not command queuing.
I tested several combinations. One adaptor failed to the point where the Pi 5 put up the boot diagnostic screen. Two adaptors reached the Pi first screen then locked up without completing the boot. Only one adaptor booted all the way. Some of the failed adaptors worked in a Pi 4.
In the Pi 4, they all worked for data access. I remember one not booting.
The one adaptor booting in the Pi 5 produced speed tests about half the speed of the Pi 5 microSD card slot. The speed difference is consistent across reads and writes, across the three measurements in the Pi Diagnostics, and across another speed test.
The cards are A1 so the difference is not command queuing.
Statistics: Posted by peterlite — Wed Jan 29, 2025 2:21 am