Deploy an hourly systemd timer that writes pool and dataset capacity to
node_exporter's textfile collector, since --collector.zfs exposes only
ARC/I-O/state. Add a provisioned 'ZFS - Pools & Datasets' dashboard with
per-pool totals, per-dataset used/quota and daily growth panels.
The variable used label_values() which lists all instances across full
retention, alphabetically sorting and auto-selecting the dead
127.0.0.1:9199 (relabeled to 'eaton' ~31h ago). Its stale series has no
samples in the visible window so every panel rendered empty. Replace with
query_result(count by (instance) (...)) which only surfaces live targets.