Out of curiosity I made a short speed comparison with a Raspberry Pi 4 running on the internal SD card vs. an external SSD (via USB3). Fun fact: the 256 GB SSD I’m using is only 4€ more expensive than the SanDisk SD with the same size. Write speed of a 400 MB file:
SD (SanDisk microSDHC UHS-I):
419430400 bytes (419 MB, 400 MiB) copied, 32.6095 s, 12.9 MB/s
SSD (SSK 256GB portable):
419430400 bytes (419 MB, 400 MiB) copied, 1.93642 s, 217 MB/s
And this is only plain write speed. Not to mention the huge general I/O speed bump and durability. Internal NVMe SSDs are even faster.
