Data ONTAP uses two methods for automatically providing more space for a FlexVol volume when that volume is nearly full: allowing the volume size to increase, and deleting Snapshot copies (with any associated storage object). If you enable both of these methods, you can specify which method Data ONTAP should try first.
This method is useful if the volume's containing aggregate has enough space to support a larger volume. You can configure Data ONTAP to increase the size in increments and set a maximum size for the volume. The increase is automatically triggered based on the amount of data being written to the volume in relation to the current amount of used space and any thresholds set.
For example, you can configure Data ONTAP to automatically delete Snapshot copies that are not linked to Snapshot copies in cloned volumes or LUNs, or you can define which Snapshot copies you want Data ONTAP to delete first—your oldest or newest Snapshot copies. You can also determine when Data ONTAP should begin deleting Snapshot copies—for example, when the volume is nearly full or when the volume’s Snapshot reserve is nearly full.
For more information about deleting Snapshot copies automatically, see the Data ONTAP Data Protection Online Backup and Recovery Guide for 7-Mode.
If you enable both of these methods, you can specify which method Data ONTAP tries first when a volume is nearly full. If the first method does not provide sufficient additional space to the volume, Data ONTAP tries the other method next. By default, Data ONTAP tries to increase the size of the volume first.