I added a new tool to the Sanoid project tonight: check_all_disk_space.
This technically isn't a ZFS tool at all; it's a generic Nagios-compatible script that checks *all* mounted filesystems, and issues OK, WARN, or CRIT based on the worst case found:
jim@banshee:~$ check_all_disk_space
OK
Simple, right? By default, WARN and CRIT are ridicu-high at 93% and 98%. Let's drop those:
jim@banshee:~$ check_all_disk_space 0.5 0.6
WARNING: /media/jim/SCARLETT: 54.3%
With appropriate exit code, ofc.