ZFS has explicit reservations: > The minimum amount of space guaranteed to a dataset and its descendants. When the amount of space used is below this value, th

ZFS has explicit reservations: > The minimum amount of space guaranteed to a dataset and its descendants. When the amount of space used is below this value, the dataset is treated as if it were taking up the amount of space specified by its reservation. Reservations are accounted for in the parent datasets' space used, and count against the parent datasets' quotas and reservations. * https://openzfs.github.io/openzfs-docs/man/8/zfsprops.8.html https://openzfs.github.io/openzfs-docs/man/8/zfsprops.8.html These are done on a per dataset basis (basically a directory delineated boundary).