4 ms·

Are you allowed to share the results of your experiment? i have a similar issue with a very limited market (SD Brands/models), it would be great if you provide

Are you allowed to share the results of your experiment? i have a similar issue with a very limited market (SD Brands/models), it would be great if you provide more info :)

monocasa 9y ago
I'd be hesitant to name any names due to NDAs and what have you. I'll just say that all consumer level cards pretty much don't really care about your data, even the good brands.
- logicallee 9y ago
  I think I speak for everyone that we really appreciate what you did share here. For how to use what you've shared if we trust you, can you throw us a bone more than: >buy 'industrial' SD cards For example can you name a specific card? Or give us enough clues that we can do so? I for one take your advice very seriously but I don't know how to use what you've just shared. I've seen ATM-style Pi-based kiosks with corrupted SD cards that wouldn't boot. It looked expensive.
  - monocasa 9y ago
    ATP Inc. has treated us very well, both their products and their support. But in general 'industrial' is the keyword to get the good shit from manufacturers who'll treat you like an adult.
  - pera 9y ago
    Search for SLC type memory cards (in the Technology filter): https://www.digikey.com/products/en/memory-cards-modules/memory-cards/501 https://www.digikey.com/products/en/memory-cards-modules/mem...
    - monocasa 9y ago
      Industrial is more than that. A big one for me was that the manufacturer will work with you and notify you when they change their BoM, letting you reverify and track internally.
  - mrsteveman1 9y ago
    Take a look at ATP, specifically the AF4GUD3A and AF8GUD3A, for 4GB and 8GB respectively. Digikey[1] and Arrow[2] generally sell the 4GB for $15 and the 8GB for $25. They make larger versions too, if you need them. The 'A' stands for aMLC, they're using normal MLC flash (which most consumer SD cards no longer use, but is generally much more reliable than TLC) but they use it in 1-bit per cell mode like SLC. They make traditional SLC cards as well, but the price skyrockets. The aMLC cards have very good endurance ratings, but they're still cheaper than SLC cards. The firmware and controller are designed to prevent sudden power loss issues, which is apparently the root cause of a lot of SD card corruption on the Pi. They're also supposed to have lifetime (i.e. SMART) monitoring, but it's a vendor specific command set rather than something smartmontools can read. ATP has a tool for it that probably only runs on Windows. I've been using those aMLC cards in a bunch of Pi3 and Pi Zero W devices for months, I've never seen them become corrupted or fail to boot even once, despite being pretty hard on them, compiling stuff, yanking the power, etc. For comparison, a Samsung Ultra+ card became corrupted after a single power loss. The device was running Windows 10 IoT Core at the time, it never booted again and had to be re-flashed. [1] https://www.digikey.com/product-detail/en/atp-electronics-inc/AF4GUD3A-OEM/AF4GUD3A-OEM-ND/5361062 https://www.digikey.com/product-detail/en/atp-electronics-in... [2] https://www.arrow.com/en/products/af4gud3a-waaxx/atp-electronics https://www.arrow.com/en/products/af4gud3a-waaxx/atp-electro...
    - sitkack 9y ago
      Could a lot of this be mitigated by having better file systems?
      - mrsteveman1 9y ago
        A small amount of it, yes, but it's the card itself causing corruption issues most of the time, it happens even on devices where the filesystem is read-only. The controller will write and move things around for maintenance purposes even if the host hasn't issued a write command. The cheap SD cards just aren't designed for anything except being used in consumer devices with batteries, where sudden power loss is rare and losing data isn't going to cause a plane to crash or result in someone not receiving a dose of insulin. So when they suddenly lose power, they aren't always capable of ensuring that whatever task they were carrying out at the time is actually completed and did not accidentally destroy data. And apparently the consumer SD card controllers are really there to manage and remap parts of the flash that were defective before ever leaving the factory. It's probably cheaper to build over-provisioned cards with a simple controller that can deal with manufacturing defects in the field, than to do QA on 200 million thumbnail sized NAND die every month and still try to profit while selling them for a fraction of a penny each.

Are you allowed to share the results of your experiment? i have a similar issue with a very limited market (SD Brands/models), it would be great if you provide more info :)

monocasa 9y ago

I'd be hesitant to name any names due to NDAs and what have you. I'll just say that all consumer level cards pretty much don't really care about your data, even the good brands.

logicallee 9y ago
I think I speak for everyone that we really appreciate what you did share here. For how to use what you've shared if we trust you, can you throw us a bone more than: >buy 'industrial' SD cards For example can you name a specific card? Or give us enough clues that we can do so? I for one take your advice very seriously but I don't know how to use what you've just shared. I've seen ATM-style Pi-based kiosks with corrupted SD cards that wouldn't boot. It looked expensive.
- monocasa 9y ago
  ATP Inc. has treated us very well, both their products and their support. But in general 'industrial' is the keyword to get the good shit from manufacturers who'll treat you like an adult.
- pera 9y ago
  Search for SLC type memory cards (in the Technology filter): https://www.digikey.com/products/en/memory-cards-modules/memory-cards/501 https://www.digikey.com/products/en/memory-cards-modules/mem...
  - monocasa 9y ago
    Industrial is more than that. A big one for me was that the manufacturer will work with you and notify you when they change their BoM, letting you reverify and track internally.
- mrsteveman1 9y ago
  Take a look at ATP, specifically the AF4GUD3A and AF8GUD3A, for 4GB and 8GB respectively. Digikey[1] and Arrow[2] generally sell the 4GB for $15 and the 8GB for $25. They make larger versions too, if you need them. The 'A' stands for aMLC, they're using normal MLC flash (which most consumer SD cards no longer use, but is generally much more reliable than TLC) but they use it in 1-bit per cell mode like SLC. They make traditional SLC cards as well, but the price skyrockets. The aMLC cards have very good endurance ratings, but they're still cheaper than SLC cards. The firmware and controller are designed to prevent sudden power loss issues, which is apparently the root cause of a lot of SD card corruption on the Pi. They're also supposed to have lifetime (i.e. SMART) monitoring, but it's a vendor specific command set rather than something smartmontools can read. ATP has a tool for it that probably only runs on Windows. I've been using those aMLC cards in a bunch of Pi3 and Pi Zero W devices for months, I've never seen them become corrupted or fail to boot even once, despite being pretty hard on them, compiling stuff, yanking the power, etc. For comparison, a Samsung Ultra+ card became corrupted after a single power loss. The device was running Windows 10 IoT Core at the time, it never booted again and had to be re-flashed. [1] https://www.digikey.com/product-detail/en/atp-electronics-inc/AF4GUD3A-OEM/AF4GUD3A-OEM-ND/5361062 https://www.digikey.com/product-detail/en/atp-electronics-in... [2] https://www.arrow.com/en/products/af4gud3a-waaxx/atp-electronics https://www.arrow.com/en/products/af4gud3a-waaxx/atp-electro...
  - sitkack 9y ago
    Could a lot of this be mitigated by having better file systems?
    - mrsteveman1 9y ago
      A small amount of it, yes, but it's the card itself causing corruption issues most of the time, it happens even on devices where the filesystem is read-only. The controller will write and move things around for maintenance purposes even if the host hasn't issued a write command. The cheap SD cards just aren't designed for anything except being used in consumer devices with batteries, where sudden power loss is rare and losing data isn't going to cause a plane to crash or result in someone not receiving a dose of insulin. So when they suddenly lose power, they aren't always capable of ensuring that whatever task they were carrying out at the time is actually completed and did not accidentally destroy data. And apparently the consumer SD card controllers are really there to manage and remap parts of the flash that were defective before ever leaving the factory. It's probably cheaper to build over-provisioned cards with a simple controller that can deal with manufacturing defects in the field, than to do QA on 200 million thumbnail sized NAND die every month and still try to profit while selling them for a fraction of a penny each.