DCO (data change object)
A Veritas Volume Manager object used to manage FastResync map information in the DCO log volume. A DCO and a DCO log volume must be associated with a volume in order to implement persistent FastResync on that volume.
A VxVM object that is used to manage information about the FastResync maps in the DCO volume. Both a DCO object and a DCO volume must be associated with a volume to implement Persistent FastResync on that volume.