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Determine space usage in a local tier (aggregate)

Contributors netapp-aherbin netapp-thomi dmp-netapp netapp-dbagwell
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You can view how much space is used by all volumes in one or more local tiers (aggregates) so that you can take actions to free more space.

WAFL reserves a percentage 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.

In aggregates smaller than 30 TB, WAFL reserves 10% of the total disk space for aggregate level metadata and performance.

Beginning with ONTAP 9.12.1, in aggregates that are 30 TB or larger, the amount of reserved disk space for aggregate level metadata and performance is reduced, resulting in 5% more usable space in aggregates. The availability of this space savings varies based on your platform and version of ONTAP.

Disk space reserved by ONTAP in aggregates 30 TB or greater Applies to platforms In ONTAP versions

5%

All AFF and FAS platforms

ONTAP 9.14.1 and later

5%

AFF platforms and FAS500f platforms

ONTAP 9.12.1 and later

10%

All platforms

ONTAP 9.11.1 and later

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.

Note Beginning with ONTAP 9.15.1, two new metadata counters are available. Together with changes to several existing counters, you can get a clearer view of the amount of user data allocated. See Determine space usage in a volume or aggregate for more information.

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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