When a snapshot backup job creates an instant clone, it creates a dependency relationship between the instant clone and the original snapshot, that is, the clone and the snapshot are coupled. Retaining the instant clone for a long period of time (months, or years) also means retaining the snapshot, which overloads the Commvault and the storage array with managing the snapshot.
To retain the instant clone without impacting performance, the decoupled instant clone feature for the Dell EMC VMAX array decouples the instant clone from the original snapshot by deleting references to it.
When you configure decoupled instant clone and the instant clone expires or is deleted, then the Commvault does not manage the instant clone anymore. When the clone is no more needed, users manually remove the clone and unmap the target devices that host the clone.
For information about the engines that you can use for instant clone, see Application Clone.