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How you can determine and control a volume's space usage in the aggregate

You can determine which FlexVol volumes are using the most space in the aggregate and specifically which features within the volume. The vol status -F command provides information about a volume's footprint, or its space usage within the containing aggregate.

The vol status -F command shows details about the space usage of each volume in an aggregate, including offline volumes. This command does not directly correspond to the output of the df command, but instead bridges the gap between the output of vol status -S and aggr status -S commands. All percentages are calculated as a percent of aggregate size.

Only non-zero values are displayed in the command output. However, you can use the -v parameter to display all possible feature rows regardless of whether they are enabled and using any space. A value of - indicates that there is no data available to display.

The following example shows the vol status -F command output for a volume called testvol:

sys1> vol status -F
Volume : testvol

      Feature                                   Used      Used%
      --------------------------------    ----------     ------
      Volume Data Footprint                   2.64GB        42%
      Volume Guarantee                        3.32GB        52%
      Flexible Volume Metadata                34.2MB         1%
      Delayed Frees                           54.8MB         1%

      Total                                   6.05GB        95%

The following table explains some of the key rows of the output of the vol status -F command and what you can do to try to decrease space usage by that feature:

Row/feature name Description/contents of row Some ways to decrease
Volume Data Footprint The total amount of space used in the containing aggregate by a volume's data in the active file system and the space used by the volume's Snapshot copies. This row does not include reserved space, so if volumes have reserved files, the volume's total used space in the vol status -S command output can exceed the value in this row.
  • Deleting data from the volume.
  • Deleting Snapshot copies from the volume.
Volume Guarantee The amount of space reserved by the volume in the aggregate for future writes. The amount of space reserved depends on the guarantee type of the volume. Changing the type of guarantee for the volume to none. This row will go to 0.

If you configure your volumes with a volume guarantee of none, you should refer to Technical Report 3965 or 3483 for information about how a volume guarantee of none can affect storage availability.

Flexible Volume Metadata The total amount of space used in the aggregate by the volume's metadata files. No direct method to control.
Delayed Frees Blocks that Data ONTAP used for performance and cannot be immediately freed.

When Data ONTAP frees blocks in a FlexVol volume, this space is not always immediately shown as free in the aggregate because operations to free the space in the aggregate are batched for increased performance. Blocks that are declared free in the FlexVol volume but that are not yet free in the aggregate are called "delayed free blocks" until the associated delayed free blocks are processed.

For SnapMirror destinations, this row has a value of 0 and is not displayed.

No direct method to control.
Total The total amount of space that the volume uses in the aggregate. It is the sum of all of the rows. Any of the methods used to decrease space used by a volume.