Whenever Snapshot copies consume more than 100% of the Snapshot reserve, they begin to occupy the active file system space. This process is called Snapshot spill. When the Snapshot copies continue to occupy the active file system space, the system is in danger of becoming full. If the system becomes full due to Snapshot spill, you can create files only after you delete enough Snapshot copies.
If 500,000 KB (0.5 GB) of data is added to the active file system, a df command generates the following output:
Filesystem kbytes used avail capacity /vol/vol0 3000000 3000000 0 100% /vol/vol0/.snapshot 1000000 3500000 0 350%
As soon as Data ONTAP creates a new Snapshot copy, every disk block in the file system is referenced by some Snapshot copy. Therefore, no matter how many files you delete from the active file system, there is still no room to add any more. The only way to recover from this situation is to delete enough Snapshot copies to free more disk space.