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Configuring a FlexVol volume to automatically change its size

You can configure a volume to grow automatically or grow and shrink automatically (known as autosizing) in response to space usage requirements. Automatic growing helps prevent a volume from running out of space or forcing you to delete files manually. Automatic shrinking prevents a volume from being larger than needed.

Before you begin

The FlexVol volume must be online.

About this task

The autosize capability is off by default, except for data protection mirrors, which have the grow_shrink option enabled by default.

You cannot configure a root FlexVol volume for the grow_shrink autosize mode.


  1. Enter the applicable command to grow the volume size automatically or to grow and shrink the volume size automatically:
    • vol autosize <vol_name> grow
    • vol autosize <vol_name> grow_shrink
    You can specify the following parameters related to growing the volume automatically:
    • -m sets the maximum size to which a volume can grow.

      The default is 120 percent of the volume size. If you resize the volume manually, this value is reset to 120 percent of the current volume size. A volume does not grow automatically if its current size is greater than or equal to the value of this option.

      If you attempt to set this parameter greater than the platform-dependent maximum volume size, it is silently reset to the maximum volume size.

    • -i specifies the amount by which the volume size increases each time the volume grows automatically.

      You can specify the increment amount either as a fixed size (in bytes) or as a percentage. The percentage is converted to a fixed size that is based on the volume size when the command is issued. The default is the lesser value of either 1 GB or 5 percent of the volume size at the time the volume was created. When increasing the size of a volume, Data ONTAP uses the specified increment as a guide; the actual size increase can be larger or smaller.

    • -grow-threshold-percent specifies the used space threshold above which growing should start.

      When the volume’s used space exceeds this threshold, the volume grows automatically unless it has reached the maximum size specified for automatic growth. The default depends on the size of the volume.

    You can specify the following parameters related to shrinking the volume automatically (in addition to the parameters related to growing):

    • -minimum size specifies the smallest size to which the volume can shrink, enabling you to maintain a percentage of free space.

      The default minimum size is the initial volume size. Manually resizing the volume or using an invalid minimum size value when you enable the autosizing feature resets this value to the current volume size.

    • -shrink-threshold percent specifies the volume's used space percent threshold below which shrinking should start.

      When the amount of used space drops below this threshold, the volume shrinks automatically unless it has reached the specified minimum size. For example, if used space is 50 percent and the threshold is 51 percent, automatic shrinking begins. The default is 50 percent.

    The command in this example enables the autosizing feature on a volume called thevol. No other parameters were specified, so the defaults are used for growing and shrinking.
    sys1> vol autosize thevol grow_shrink
    vol autosize: Flexible volume 'thevol' autosize settings UPDATED.
    sys1> Fri Nov 30 02:42:02 GMT [sys1:wafl.spacemgmnt.policyChg:info]: The space 
    management policy for volume thevol has changed: autosize state enabled.