Defining a space management policy

What space management policies are

A space management policy enables you to automatically reclaim space for a FlexVol volume when that volume is nearly full. You can configure a FlexVol volume to automatically reclaim space by using the following policies:

Grow a FlexVol volume automatically when it is nearly full.
This policy is useful if the containing aggregate has enough space to grow the FlexVol volume. You can grow a volume in increments and set a maximum size for the volume.
Automatically delete Snapshot copies when the FlexVol volume is nearly full.
For example, you can automatically delete Snapshot copies that are not linked to Snapshot copies in cloned volumes or LUNs, or you can define which Snapshot copies you want to delete first--your oldest or newest Snapshot copies. You can also determine when to begin deleting Snapshot copies--for example, when the volume is nearly full or when the volume's Snapshot copy reserve is nearly full.

You can define the order in which you want to apply these policies when a FlexVol volume is running out of space. For example, you can automatically grow the volume first, and then begin deleting Snapshot copies, or you can reclaim space by first automatically deleting Snapshot copies, and then growing the volume.

Configuring a volume to grow automatically

To configure a volume to grow automatically, complete the following step.

Step	Action
1	Enter the following command: *vol autosize vol-name* [-m size] [-i size] [on\|off\|reset]** vol-name is the name of the FlexVol volume. You cannot use this command on traditional volumes. `-m` size is the maximum size to which you can grow the volume. Specify a size in `k` (KB), `m` (MB), `g` (GB) or `t` (TB). The volume does not grow if its size is equal to or greater than the maximum size. `-i` size is the increment by which you grow the volume. Specify a size in `k` (KB), `m` (MB), `g` (GB) or `t` (TB). `on` enables the volume to automatically grow. `off` disables automatically growing the volume. By default, the `vol autosize` command is set to Off. `reset` restores the `autosize` settings of the volume to the default setting, which is Off.

Step

Action

Enter the following command:

vol autosize vol-name [-m size] [-i size] [on|off|reset]

vol-name is the name of the FlexVol volume. You cannot use this command on traditional volumes.

-m size is the maximum size to which you can grow the volume. Specify a size in k (KB), m (MB), g (GB) or t (TB). The volume does not grow if its size is equal to or greater than the maximum size.

-i size is the increment by which you grow the volume. Specify a size in k (KB), m (MB), g (GB) or t (TB).

on enables the volume to automatically grow.

off disables automatically growing the volume. By default, the vol autosize command is set to Off.

reset restores the autosize settings of the volume to the default setting, which is Off.

Automatically deleting Snapshot copies

Defining a policy for deleting Snapshot copies

To define a policy, complete the following step:

Step	Action
1	Enter the following command: snap autodelete vol-name option value Define which Snapshot copies you delete by entering the following options and their values:
	Option	Values
	`commitment`	Specifies whether a Snapshot copy is linked to data protection utilities (SnapMirror, Dump, or NDMPcopy) or data backing mechanisms (volume or LUN clones). `try`--delete only Snapshot copies that are not linked to data protection utilities and data backing mechanisms. `disrupt`--delete only Snapshot copies that are not linked to data backing mechanisms.
	`trigger`	Defines when to begin automatically deleting Snapshot copies. `volume`--begin deleting when the volume is nearly full. `snap_reserve`--begin deleting when the snapshot reserve is nearly full. `space_reserve`--begin deleting when the space reserved in the volume is nearly full.
	`target_free_space`	Determines when to stop deleting Snapshot copies. Specify a percentage. For example, if you specify 30, then Snapshot copies are deleted until 30 percent of the volume is free space.
	`delete_order`	`newest_first`--delete the most recent Snapshot copies first. `oldest_first`--delete the oldest Snapshot copies first.
	`defer_delete`	Delete one of the following types of Snapshot copies last: `scheduled`--scheduled Snapshot copies, which are identified by their naming convention. `user_created`--Snapshot copies that are not scheduled Snapshot copies `prefix`--Snapshot copies with a prefix matching the specified `prefix_string` value
	`prefix`	Delete Snapshot copies with a specific prefix last. You can specify up to 15 characters (for example, sv_snap_week). Use this option only if you specify `prefix` for the `defer_delete` option, otherwise the value you set for prefix is not applied.

Enabling the Snapshot copy autodelete policy

To enable the Snapshot copy autodelete policy you define, complete the following step.

Step	Action
1	Enter the following command: *snap autodelete vol-name* on**

Viewing current Snapshot copy autodelete settings

To view current autodelete settings, complete the following step:

Step	Action
1	Enter the following command: *snap autodelete vol-name* show**

Restoring default Snapshot copy autodelete settings

To restore default Snapshot copy autodelete settings, complete the following step:

Step	Action
1	Enter the following command: *snap autodelete vol-name* reset** vol-name is the name of the volume. Result Snapshot autodelete settings revert to the following defaults: state--off commitment --try trigger--volume target_free_space-- 20% delete_order--oldest_first defer_delete--user_created prefix-- no prefix specified

Step

Action

Enter the following command:

snap autodelete vol-name reset

vol-name is the name of the volume.

Result

Snapshot autodelete settings revert to the following defaults:

state--off
commitment --try
trigger--volume
target_free_space-- 20%
delete_order--oldest_first
defer_delete--user_created
prefix-- no prefix specified

Disabling a Snapshot copy autodelete policy

Complete the following step:

Step	Action
1	Enter the following command: *snap autodelete vol-name* off** vol-name is the name of the volume. Result Snapshots are not automatically deleted when the volume is nearly full.

Defining how you apply space management policies

You can configure Data ONTAP to apply space management policies in one of the following ways:

Automatically grow the volume first, then automatically delete Snapshot copies.
This approach is useful if you create smaller FlexVol volumes and leave enough space in the aggregate to increase the size of these volumes as needed. If you provision your data based on aggregates, you might want to automatically grow the volume when it is nearly full before you begin automatically deleting Snapshot copies.
Automatically delete Snapshot copies first, then grow the volume.
You might want to automatically delete Snapshot copies if you are maintaining a large number of Snapshot copies in your volume or you maintain older Snapshot copies that are no longer needed.

To determine how Data ONTAP applies space management policies, complete the following step:

Step	Action
1	Enter the following command. *vol options vol-name* try_first [volume_grow\|snap_delete]** vol-name is the name of the FlexVol volume `volume_grow`--Automatically increase the size of the FlexVol volume before automatically deleting Snapshot copies. `snap_delete`--Automatically delete Snapshot copies according to the policy you defined in Automatically deleting Snapshot copies before automatically increasing the size of the volume.

Step

Action

Enter the following command.

vol options vol-name try_first [volume_grow|snap_delete]

vol-name is the name of the FlexVol volume

volume_grow--Automatically increase the size of the FlexVol volume before automatically deleting Snapshot copies.

snap_delete--Automatically delete Snapshot copies according to the policy you defined in Automatically deleting Snapshot copies before automatically increasing the size of the volume.