4 ms·

We have hundreds of raspberry pi s out in the field that experience sdcard failures far too often even though the filesystems are setup as readonly using a ram

We have hundreds of raspberry pi s out in the field that experience sdcard failures far too often even though the filesystems are setup as readonly using a ram based overlay filesystem. I suspect something happens during reboot of these pi's and that the SoC generates spurious signals on the bus lines causing havoc with some of the sdcards. It doesn't seem to happen with high end cards or the same setup but with a compute module (which we now use exclusively) with an on board emmc chip.

dezgeg 2y ago
Are there other SBCs / SoMs that are as widely used with SD cards though? That's certainly a source of bias.
- imtringued 2y ago
  99% of devices that use SD cards are battery powered. It's an issue with the power supply.
OptionOfT 2y ago
This is interesting, I got gifted an one of those hydroponic systems. The thing was 2 years old. Runs on a Raspberry Zero. The issue? SD card corrupt. I got an image from someone else and fixed it with that. What's worse is that these things are connected to the internet (with VNC installed!), and they don't do updates... The system is awesome, but I VERY quickly moved it to a separate VLAN.
lysace 2y ago
These haven't failed for me: https://www.digikey.com/en/product-highlight/a/atp/advancedmlc-amlc-microsd-microsdhc-cards https://www.digikey.com/en/product-highlight/a/atp/advancedm... I'm cynically guessing it's down to a relatively simple workaround in the SD card firmware that fixes this very common corruption on power loss while writing. Or maybe that combined with a 0.1 cent capacitor.
lxgr 2y ago
Writes aren't the only things that can degrade data stored on NAND flash. Not sure how SD cards are mitigating read disturb errors, for example.
erik 2y ago
I've seen the same. I don't think it's the reboot. My understanding is that NAND undergoes wear-leveling even when it is read only. The card shuffles data around its storage even when it hasn't been written to. And the firmware is unreliable.

dezgeg 2y ago

Are there other SBCs / SoMs that are as widely used with SD cards though? That's certainly a source of bias.

imtringued 2y ago
99% of devices that use SD cards are battery powered. It's an issue with the power supply.

OptionOfT 2y ago

This is interesting, I got gifted an one of those hydroponic systems. The thing was 2 years old. Runs on a Raspberry Zero. The issue? SD card corrupt. I got an image from someone else and fixed it with that. What's worse is that these things are connected to the internet (with VNC installed!), and they don't do updates... The system is awesome, but I VERY quickly moved it to a separate VLAN.

lysace 2y ago

These haven't failed for me: https://www.digikey.com/en/product-highlight/a/atp/advancedmlc-amlc-microsd-microsdhc-cards https://www.digikey.com/en/product-highlight/a/atp/advancedm... I'm cynically guessing it's down to a relatively simple workaround in the SD card firmware that fixes this very common corruption on power loss while writing. Or maybe that combined with a 0.1 cent capacitor.

lxgr 2y ago

Writes aren't the only things that can degrade data stored on NAND flash. Not sure how SD cards are mitigating read disturb errors, for example.

erik 2y ago

I've seen the same. I don't think it's the reboot. My understanding is that NAND undergoes wear-leveling even when it is read only. The card shuffles data around its storage even when it hasn't been written to. And the firmware is unreliable.