Stoker

Settings
Dashboard Events

Alert channels

Events at or above the minimum severity are sent to every configured channel.

Email (SMTP)

Disk space

Agents already report every fixed volume. These thresholds decide when a full disk becomes an alert, and they apply to every machine in the fleet.
Both halves must be true. Percentage alone misfires at scale: 2% free on a 50 TB array is a terabyte, which is not an emergency, while 5% free on a 100 GB system disk is. The free-space figure is what makes one setting safe across volumes of wildly different sizes. Set it to 0 to go back to percentage only.
Small volumes are skipped by default because EFI and recovery partitions sit near full by design and would alert on every machine you install. A volume has to climb clear of a threshold before it counts as recovered, so a disk hovering on the line does not alert and clear repeatedly. Going from warning to critical always notifies immediately, wherever the reminder schedule has got to.