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How you can determine and control space usage in a volume

You can view details about space usage in a volume to understand which Data ONTAP features are consuming space and what you can do to decrease that used space.

The vol status -S command displays the space used by each of the file system components as well as other features. The vol status -S command includes offline volumes. For example, you might want to understand why the df command output shows that a large amount of space is still used even though you deleted all of your data in a volume. In this case, output for the volume space usage command might show that it is due to Snapshot copies, inodes, or other metadata that does not shrink.

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 tables explain some of the common rows in the vol status -S command output and what you can do to try to decrease space usage by that feature:

The output for this command consists of the following main categories:

For information about how to reduce space consumed by other features (such as deduplication), see the respective Data ONTAP guides.

The available space in a volume with a guarantee type of None is limited by the available space in the aggregate. Checking the available space in the aggregate might show you that the aggregate is nearly full from aggregate Snapshot copies.

User data

The following output row relates to user data:

Row/feature name Description Some ways to decrease space usage
User Data Everything related to user data, including the data written to the volume, including indirect blocks and directory blocks associated with user inodes, and the space reserved in the volume.
  • Deleting user data
  • Turning off file or LUN reservations

    Note that turning off file or LUN reservations disables Data ONTAP's ability to guarantee writes to those files or LUNs. This can result in out of space errors being returned. Turning off reservations should be a temporary measure, and reservations should be reenabled as soon as you have provided more free space to the volume.

Volume metadata

The following output rows relate to volume metadata:

Row/feature name Description Some ways to decrease space usage
Deduplication / Deduplication Percent The amount of space used by deduplication metadata files. Comparison of the space savings you are getting from deduplication with the size of the metadata required. If the metadata requirement is larger than the savings, you can disable deduplication on the volume.
Temporary Deduplication / Temporary Deduplication Percent The amount of space used by temporary deduplication metadata files. No direct method to control. The temporary metadata usage decreases after deduplication scanners finish running.
Filesystem Metadata / Filesystem Metadata Percent Internal tracking for the file system required by Data ONTAP. No direct method to control.
SnapMirror Metadata / SnapMirror Metadata Percent The amount of space in use by SnapMirror metadata files. This row relates only to logical replication. During transfers, some additional space is used temporarily. No direct method to control.

You can allow the transfer to finish so the additional space used temporarily is freed.

Tape Backup Metadata / Tape Backup Metadata Percent The amount of space in use by tape backup metadata files in the volume. The amount of space consumed by tape backup metadata is cleared when the next baseline (Level 0) backup is successfully run. You can initiate a baseline backup or let it run at the next scheduled time.
Quota Metadata / Quota Metadata Percent The amount of space used by quota metadata files. Turning off quotas.
Inodes / Inodes Percent

This row is proportional to the maximum number of files ever created in the volume.

No direct method to control current usage.

You can reduce the maximum amount of space that can be used for inode allocations by lowering the maximum public inode setting (maxfiles). However, space that has already been allocated for inodes is never returned to the volume, so if those inodes have already been used, this action has no effect.

Snapshot copy information

The following output rows relate to Snapshot copies:

Row/feature name Description Some ways to decrease space usage
Snapshot Reserve Based on the current volume size. The Snapshot reserve is not available to the active file system and is counted as used space, even if there are no Snapshot copies in the reserve.

This row is the same as the total space used for the .snapshot row in the df command.

You can use the snap reserve command with the percent option to lower the space allowed for Snapshot copies in the volume.

Snapshot Spill The amount of space used by Snapshot copies that exceeds the Snapshot reserve size, and spills over into the active file system. This space is not available for writes to the active file system until Snapshot copies are deleted.

A non-zero value in this row indicates that your Snapshot reserve has not been sized correctly for your current configuration.

Volume clones, SnapMirror, and regularly scheduled Snapshot copies can cause Snapshot copy spill.

  • Increasing the size of the Snapshot reserve.
  • Deleting volume Snapshot copies, either manually or by enabling the Snapshot autodelete capability.
  • Changing the SnapMirror schedule.

Total used space

The following row relates to total used space in the volume:

Row/feature name Description Some ways to decrease space usage

Total

The total amount of used space in the volume, including the amount of space allotted for the entire Snapshot reserve and space for the active file system.

Snapshot space is treated as used space, so this row can be higher than the df command's output. In the df command, this row is equivalent to the volume's used space in the used column plus the Snapshot total (in the total column) for the Snapshot used space (.snapshot) row.

When Snapshot spill exists, the vol status -S command only accounts for the used space once. However, the df command shows that space as used for both the active file system and for the .snapshot row.

Any of the methods for individual output rows.

Example output

The following is an example of command output for a FlexVol volume called testvol.

sys1> vol status -S
Volume : testvol

      Feature                                   Used      Used%
      --------------------------------    ----------     ------
      User Data                               2.40GB        40%
      Filesystem Metadata                     1.07MB         0%
      Inodes                                  2.63MB         0%
      Snapshot Reserve                         308MB         5%

      Total                                   2.71GB        45%