When you take a Snapshot copy of a LUN, it is initially backed by data in the Snapshot copy. After the Snapshot copy is taken, data written to the LUN is available in the active file system.
After you have a Snapshot copy, you can use it to create a LUN clone for temporary use as a prototype for testing data or scripts in applications or databases. Because the LUN clone is backed by the Snapshot copy, you cannot delete the Snapshot copy until you split the clone from it.
To restore the LUN from a Snapshot copy, use SnapRestore. However, keep in mind that the restored LUN will not have any data that was written after the Snapshot copy was made.
Space reservations might prevent you from taking a Snapshot copy: In Data ONTAP 6.5 and later, space reservation is enabled by default when you create a LUN. This means that enough space is reserved so that write operations to the LUNs are guaranteed. The more space that is reserved, the less free space is available. If free space within the volume is below a certain threshold, Snapshot copies cannot be taken.
For information about how to manage available space, see the Data ONTAP Block Access Management Guide.