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What is volume autosize in Data ONTAP?

Applies to

  • ONTAP 9
  • Data ONTAP 8
  • Data ONTAP 8 7-Mode
  • Data ONTAP 7 and earlier

Answer

What does volume autosize do?

  • Volume autosize is a policy-based space-management feature in Data ONTAP that allows the volume to grow by an increment if the volume is nearly full.
  • The nearly full threshold is defined by the flag wafl_reclaim_threshold.
  • When a write is sent to the node that is larger than available space, Data ONTAP will try to write as much as possible before failing the write with a volume full message.  During the next check, the volume will grow by increments until it has reached the minimum free space threshold.  This means that autosize is best described as 'grow on use,' rather than 'grow on demand,' a distinction that should be remembered when planning thresholds and grow increments.
  • Note that volume autosize does not infinitely grow the volume.  The volume will grow until it reaches the maximum autosize value and then no more space will be allocated.

 

The syntax for enabling volume autosize is as follows:

  • Data ONTAP 7:

> vol autosize  [-m [k|m|g|t]]
               [-i [k|m|g|t]] 
              [ on | off | reset ]

-m option sets the maximum size a volume is permitted to grow. Default setting is 120% of volume size at the time of creation
-i option defines the increment by which a volume is grown every time the volume is full. Default setting is 5% of volume size at the time of creation
on enables the feature
off disables the feature
reset resets the settings to default value.

 

  • Data ONTAP GX:

volume modify -vserver -volume
           [-autosize {true | false}]
           [-max-autosize maximum_autosize]
           [-autosize-increment increment_size]

-autosize optionally specifies whether automatic sizing is enabled for the volume
-max-autosize optionally specifies the maximum automatic size for the volume
-autosize-increment optionally specifies the increment for automatic sizing.

 

  • Clustered Data ONTAP/ONTAP 9:

::> volume modify -vserver <vserver_name> -volume <volume_name> -autosize
-autosize-increment                -autosize-increment-percent
-autosize-grow-threshold-percent   -autosize-shrink-threshold-percent
-autosize-mode                     -autosize
-autosize-reset                    -antivirus-on-access-policy

Note: Starting in ONTAP 9, -autosize-increment is unavailable, as this value is dynamically determined by ONTAP.

For more details on above parameters check the below link:

https://library.netapp.com/ecmdocs/ECMP1196817/html/volume/autosize.html

 

Choosing reclaim policies:

In order to reclaim space which is determined by defining policies, with the use of the try_first volume option. The try_first volume option determines whether:

  • Snapshot autodelete would be attempted first.
  • Or volume autosize would be attempted first.

The possible try_first values are:

  • snap_delete
  • volume_grow