You can impose a storage limit, called a quota, on a directory. The quota configuration includes a hard limit, and, optionally, a soft limit and a grace period.
When a directory's soft limit is reached, the alarm "SOFT_EXCEEDED" is triggered.
If the directory remains in excess of the soft limit for the time defined as the grace period, an additional alarm, "GRACE_EXPIRED," is triggered and the directory is blocked to writes.
If the directory reaches the hard limit, the alarm "HARD_EXCEEDED" is triggered, and the directory is blocked to writes.