I've been having issues for a while now and haven't figured out the cause. It seems anytime I have an unclean shutdown from a power failure during the parity check one of my drives will start reporting errors and eventually get disabled. At first I thought maybe it was a power issue but now I believe it may be my HBA card or the controller in the disk shelf.
My current issue is during a parity rebuild another disk starting having I/O errors and then showed up under "Unassigned Devices" even though the rebuild was still running. After the rebuild finished this disk was now disabled and like an idiot I click on mount in "Unassigned Devices" but it did not mount. I checked the actual disk shelf to make sure the drive was properly connected and rebooted unraid. After rebooting this disk now says "disabled/emulated" but also says Unmountable No file system. Is there a way to recover from this within unraid or should I remove the disk and copy the data off, then allow unraid to reformat it? Below is the log info for the disk and attach is the diagnostics.
Aug 27 16:14:00 nas emhttpd: shcmd (150): mkdir -p /mnt/disk19
Aug 27 16:14:00 nas emhttpd: shcmd (151): mount -t btrfs -o noatime,nodiratime /dev/md19 /mnt/disk19
Aug 27 16:14:00 nas kernel: BTRFS info (device md19): disk space caching is enabled
Aug 27 16:14:00 nas kernel: BTRFS info (device md19): has skinny extents
Aug 27 16:14:01 nas kernel: BTRFS error (device md19): bad tree block start 9784718863715718926 2751066292224
Aug 27 16:14:01 nas kernel: BTRFS error (device md19): failed to recover balance: -5
Aug 27 16:14:01 nas root: mount: /mnt/disk19: wrong fs type, bad option, bad superblock on /dev/md19, missing codepage or helper program, or other error.
Aug 27 16:14:01 nas kernel: BTRFS error (device md19): open_ctree failed
Aug 27 16:14:01 nas emhttpd: shcmd (151): exit status: 32
Aug 27 16:14:01 nas emhttpd: /mnt/disk19 mount error: No file system
Aug 27 16:14:01 nas emhttpd: shcmd (152): umount /mnt/disk19
Aug 27 16:14:01 nas root: umount: /mnt/disk19: not mounted.
Aug 27 16:14:01 nas emhttpd: shcmd (152): exit status: 32
Aug 27 16:14:01 nas emhttpd: shcmd (153): rmdir /mnt/disk19
nas-diagnostics-20180827-2318.zip