I have discovered a issue using V30 SD cards causing the SD card getting unreadable.
I have attached the PiS on USB Hub for power supply. On PiS 5V there is an ADA1701 and Arduino Nano, LCD Display and some LEDs. The maximal total Current was 420 mA at 4.92V Everything was fine.
After changing my SD Card to a faster one, now Sandisc Extreme V30, I have seen a lot of crashes while writing on SD cards. For example using apt-get on large packets. 2 Time the filesystem was corrupt and PI won’t boot anymore.
The SD card may take 1.4 Watts additional power. I saw that I have a peek current to 680 mA. Means only the SD card consumes 260 mA extra current while writing.
This leads to a voltage drop under 4.2 V causing the PiS doing a reset. This reset while writing corrupts the file system.
I think, that the current peak for erasing blocks will not buffered by capacitors, when there are to fast.
After adding a extra 1000uF and a better power source solve the issue.
So be warned. When using this V30 cards be sure that your power source can handle this current peeks.