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What can impact snapshot size and cause snapshot spill

Last Updated:

Applies to

  • Data ONTAP operating in 7-Mode
  • Clustered Data ONTAP 8
  • ONTAP 9
  • Snapshots
  • Cloud Volume Ontap


  • The more the active file system changes and the longer Snapshot copies remain, the more space the copies consume.
  • This is due to the fact that WAFL never overwrites a data block.
  • If a file is modified, updated blocks are written to a new location.
  • If data gets deleted from the active file system, old snapshot copies that contain that data will still point to those blocks, thus, space will not get freed up.
  • Therefore, snapshots can become larger and grow beyond their snap reserve, thus, spilling into AFS (Active File System).
  • If this happens, the user can use one (or a combination) of the following options:
  1. Increase snap reserve (Increase volume's size or enable volume's autosize mode)
  2. Change the Snapshot retention rate
  3. Configure Snapshot autodelete
  4. Backup Snapshots to DR
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