Local replication is generally grouped into three technology categories: full-volume mirroring, pointer-based full-volume replication, and pointer-based virtual replication. A clone corresponds to pointer-based full-volume replication: at the moment of creation it initially uses pointers back to the source volume for data not yet physically copied, and a background process progressively copies all data over so that the clone eventually becomes a fully independent, complete copy that can survive the loss of the source. This initial reliance on pointers, followed by full materialization, is the specific characteristic behind the 'pointer-based' classification for clones within EMC/Dell replication terminology. A mirror (D) describes full-volume mirroring, where the target is a continuously synchronized, complete copy from the outset, with no pointer-based intermediate state. Snapshot (A) is technically also pointer-based, but it is classified separately as pointer-based virtual replication, since a snapshot never becomes a fully independent copy and instead continuously depends on pointers to the source plus a repository of changed blocks for its lifetime. Asynchronous replication (B) describes a timing mode (how quickly writes propagate) applicable to remote replication generally, not a local, pointer-based replication technology itself. Clone is the term specifically associated with pointer-based full-volume replication in this curriculum.

Reference topic: Replication and Data Archiving - Local Replication Technologies (Mirror, Clone, Snapshot).