What logical space enforcement does
When you enable logical space enforcement in ONTAP 9.5 and later, ONTAP counts the logical-used blocks in a volume to determine the amount of space that is still available in that volume. If there is no space available in a volume, the system returns an ENOSPC (out-of-space) error message.
Logical space enforcement ensures that users are notified when a volume is full or nearly full. Logical space enforcement returns three types of alerts to inform you about the available space in a volume:
Monitor.vol.full.inc.sav: This alert is triggered when 98% of the logical space in the volume has been used.
Monitor.vol.nearFull.inc.sav: This alert is triggered when 95% of the logical space in the volume has been used.
Vol.log.overalloc.inc.sav: This alert is triggered when the logical space used in the volume is greater than the total size of the volume.
This alert tells you that adding to the size of the volume might not create available space since that space will already be consumed by overallocated logical blocks.
Total (logical space) should be equal to provisioned space excluding Snapshot reserve of the volume with logical space enforcement.
For more information, see Configuring volumes to automatically provide more space when they are full