Hard quotas prevent operations while soft quotas trigger notifications.
Hard quotas impose a hard limit on system resources; any operation that would result in exceeding the limit fails. The following settings create hard quotas:
Soft quotas send a warning message when resource usage reaches a certain level, but do not affect data access operations, so you can take appropriate action before the quota is exceeded. The following settings create soft quotas:
Threshold and Soft Disk quotas enable administrators to receive more than one notification about a quota. Typically, administrators set the Threshold to a value that is only slightly smaller than the Disk limit, so that the threshold provides a "final warning" before writes start to fail.