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How FlexClone files and FlexClone LUNs work

FlexClone files and FlexClone LUNs share the same physical data blocks with their parent files and LUNs present in FlexVol or FlexClone volumes, and occupy negligible space in the form of metadata.

You can create a clone of a file that is present in a FlexVol volume in a NAS environment, and you can also clone a LUN in a SAN environment.

The cloned copies are highly space-efficient and time-efficient because the cloning operation does not copy physical blocks of data. When you write new data to a parent or clone, then the entity on which new data is written starts occupying extra storage space.

The following illustration shows the parent files or LUNs and FlexClone files or LUNs accessing the same data blocks on the storage system. On the host side, the parent files or LUNs and FlexClone files or LUNs appear as normal files and LUNs:


The cloning operation is instantaneous and has no impact on client access to the parent file or LUN. Clients that are accessing the parent file or LUN do not experience any disruption or outage. Clients can perform all operations on FlexClone files and FlexClone LUNs as they can on standard files and LUNs.

You can create a maximum of 32,767 FlexClone files or FlexClone LUNs from a parent file or LUN without creating a physical copy of the parent entity. If you try to create more than 32,767 clones, Data ONTAP automatically creates a new physical copy of the parent file or LUN.
Note: FlexClone LUNs are not the same as LUN clones. You can create a FlexClone LUN without a backing Snapshot copy of the parent LUN. However, to create a LUN clone, you must have a backing Snapshot copy of the parent LUN. For more information about LUN clones, see the Data ONTAP SAN Administration Guide for 7-Mode.