ABS supports two cloning methods: from volume to volume, and from snapshot to volume. The two methods differ in the following ways:
Cloning from volume to volume
This operation is similar to taking a snapshot of a volume. The main difference is that cloning creates a new read-write volume, whereas a snapshot creates an immutable data block table that records the data state. The clone operation copies the structure of the source volume, creating a new volume capable of executing I/O, identical to the source volume. Each extent of the cloned volume contains a COW mark bit.
Cloning from snapshot to volume
This operation creates a new volume based on a snapshot. A snapshot itself saves a static data table of the original volume at a specific moment. Therefore, cloning from a snapshot to a volume creates a new volume based on the snapshot, allowing read and write operations. Each extent of the new volume also contains a COW mark bit, ensuring that it does not alter the original snapshot content during modifications.
