NAND becomes corrupted after operating time

    Hello,


    We are testing 10 machines with armStoneA9r2 hardware and NAND memory. Of those 10 machines, 70% of them crash after a week, the X server stops working or there are kernel panics, .....

    Further investigation shows that some units are corrupting blocks according to the FASTBOOT. See photo:




    On other drives according to FASTBOOT there are no bad blocks but when booting buildroot it reports severe failures in the UBIFS file system.


    Have you heard of other users experiencing this problem?

    Could it be that our '/' partition is mounted in read-write and when writing over time we end up corrupting the NAND memory?

    Should we test with the '/' partition mounted in read-only?


    Thank you.

    When using writable filesystems, you *must* shut down the device properly. Otherwise, if the device is only switched off, there will definitely be corrupted filesystems after some time.


    If you can not guarantee that the device is always shut down correctly, then you can never be 100% sure. You can only try to keep inconsistent times as short as possible to reduce the probability for problems. For example by keeping all filesystems read-only and only remounting them temporary to writable when actually writing data and remounting them again to read-only after that. Or have an extra partition (or UBI volume) where the written data is located and where it does not matter if this partition/volume gets corrupted.


    There is a big misunderstanding of filesystems. Yes, UBIFS is a so-called Journaling Filesystem. This means if it is inconsistent when starting up, for example because it was not properly shut down, it can be brought back to a consistent state by simply examining the Journal. So it does not require a full filesystem check for this. But this does *not* mean that you do not lose any data during this process!


    Your F&S Support Team

    F&S Elektronik Systeme GmbH
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