ONTAP 9.14

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Determine space usage in a local tier (aggregate)

You can view how much space is used by all of the volumes in one or more local tiers (aggregates) so that you can take actions to free more space.

WAFL reserves 10% of the total disk space for aggregate level metadata and performance. The space used for maintaining the volumes in the aggregate comes out of the WAFL reserve and cannot be changed.

Beginning in ONTAP 9.12.1 and later, the WAFL reserve for aggregates greater than 30TB is reduced from 10% to 5% for ETERNUS AX/AC series. Beginning in ONTAP 9.14.1, this same reduction applies to aggregates on all ETERNUS HX series, resulting in 5% more usable space in the aggregates.

You can view space usage by all volumes in one or more aggregates with the aggregate show-space command. This helps you see which volumes are consuming the most space in their containing aggregates so that you can take actions to free more space.

The used space in an aggregate is directly affected by the space used in the FlexVol volumes it contains. Measures that you take to increase space in a volume also affect space in the aggregate.

The following rows are included in the aggregate show-space command output:

  • Volume Footprints

    The total of all volume footprints within the aggregate. It includes all of the space that is used or reserved by all data and metadata of all volumes in the containing aggregate.

  • Aggregate Metadata

    The total file system metadata required by the aggregate, such as allocation bitmaps and inode files.

  • Snapshot Reserve

    The amount of space reserved for aggregate Snapshot copies, based on volume size. It is considered used space and is not available to volume or aggregate data or metadata.

  • Snapshot Reserve Unusable

    The amount of space originally allocated for aggregate Snapshot reserve that is unavailable for aggregate Snapshot copies because it is being used by volumes associated with the aggregate. Can occur only for aggregates with a non-zero aggregate Snapshot reserve.

  • Total Used

    The sum of all space used or reserved in the aggregate by volumes, metadata, or Snapshot copies.

  • Total Physical Used

    The amount of space being used for data now (rather than being reserved for future use). Includes space used by aggregate Snapshot copies.

The following example shows the aggregate show-space command output for an aggregate whose Snapshot reserve is 5%. If the Snapshot reserve was 0, the row would not be displayed.

cluster1::> storage aggregate show-space

						Aggregate : wqa_gx106_aggr1

      Feature                                   Used      Used%
      --------------------------------    ----------     ------
      Volume Footprints                      101.0MB         0%
      Aggregate Metadata                       300KB         0%
      Snapshot Reserve                        5.98GB         5%

      Total Used                              6.07GB         5%
      Total Physical Used                    34.82KB         0%
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