I'm getting similar symptoms on Ubuntu 14.04 64bit. A Samsung 64GB microSD card, was able to browse and delete files normally, but when copy about 48GB to it, it would hang around 10GB (my system has 16GB of RAM). The processing mount.exfat then would cause high iowait. I ejected the card, put it back in and was able to read it again, but there was only about 300MB of data written to it.
See attached log copied from dmesg. ** Attachment added: "error log from dmesg" https://bugs.launchpad.net/ubuntu/+source/udev/+bug/1384969/+attachment/4416067/+files/microsd_copy_error.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1384969 Title: Writing large amounts of data to exFAT formatted micro sdcards with Ubuntu causes kernel errors and permanent sdcard failure. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/udev/+bug/1384969/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
