I'm seeing this:
/var/log/syslog.2:May 30 00:41:50 unraid kernel: BTRFS: error (device loop2) in btrfs_replay_log:2277: errno=-5 IO failure (Failed to recover log tree)
/var/log/syslog.2:May 30 00:42:57 unraid kernel: BTRFS: error (device md1) in btrfs_finish_ordered_io:3069: errno=-5 IO failure
/var/log/syslog.2:May 30 00:43:01 unraid kernel: BTRFS: error (device loop2) in btrfs_commit_transaction:2236: errno=-5 IO failure (Error while writing out transaction)
The drive is an SSD. The server got unplugged while doing lots of I/O. Logs attached.
If it comes down to it, I believe I've got a good backup from a few days prior, but I'd rather try to recover from this than go through that.
unraid-diagnostics-20190607-1954.zip