After a snapshot is created, there are two scenarios for the virtual machine (VM) to read data:

If the data to be read is data that existed before snapshot creation and has not been modified since the snapshot was created, it will be read from the source virtual disk.

If the data to be read is data added or modified after snapshot creation, it will be read from the snapshot space.

The data read process after snapshot creation is as follows:

①The VM issues a data read command. When reading the snapshot, the snapshot system determines whether the data exists in the snapshot.

②To read data "a" corresponding to the original address "1" — which is data from before snapshot creation, and address "1" does not exist in the mapping table — the system is directly redirected to the source volume, reads from the source volume, and returns data "a".

③ To read data "e" corresponding to the original address "2" — which is a data area that has been written to after snapshot creation — the system reads from the snapshot space and returns data "e".