Btrfs.monitor

The BTRFS monitor takes a list of mount points for BTRFS filesystems on the command-line and checks how many errors there have been via the "btrfs device stats" command. If there have been errors then it looks for a file named /var/lib/mon/btrfs-$MOUNTPOINT.count and gives an alert if that file doesn't exist or if the number in that file is less than the number of errors. This is so that if a filesystem has a few errors and you think that's OK you can count that as being OK. If you are monitoring the root filesystem then /var/lib/mon/btrfs-root.count will have the count.