There’s an excellent benchmarking post on SD card performance on Raspberry Pi’s by Jeff Geerling. These are the results of tests on my SD cards.
I’ve created a script that runs Jeff’s test here.
hdparm is a sequential read test, nice for quick boot
dd write is a block read/write test
| Type | Device | hdparm | dd write | 4k rand read | 4k rand write |
|---|---|---|---|---|---|
| USB SSD | WD PiDrive 314 | 17.93 MB/s | 36.3 MB/s | 0.466 MB/s | 1.5 MB/s |
| Micro SDHC | 16GB Samsung Pro | tbd | tbd | tbd | tbd |
| USB | 128GB SanDisk USB | 33.25 MB/s | 21.7 MB/s | 2.53 MB/s | 1.53 MB/s |
| USB | 64GB Trascend USB | 35.56 MB/s | 15.2 MB/s | 4.08 MB/s | 0.62 MB/s |
| Micro SDHC | 32GB Samsung EVO | 20.17 MB/s | 15.0 MB/s | 8.61 MB/s | 3.05 MB/s |
| Micro SDHC | 8GB SanDisk | 21.64 MB/s | 9.8 MB/s | 7.51 MB/s | 0.76 MB/s |
| Micro SDHC | 32GB GSkill | 20.6 MB/s | 16.3 MB/s | 4.0 MB/s | 0.6 MB/s |
| Micro SDHC | 16GB Samsung EVO | 9.82 MB/s | 11.7 MB/s | ||
| Micro SDHC | 32GB SP | 17.83 MB/s | 10.3 MB/s | 2.5 MB/s | 0.25 MB/s |