An iscsi snapshot is a point-in-time view of the data on an associated iscsi volume. Iscsi snapshots use a copy-on-write technology to minimize the amount of snapshot space used. When a snapshot is initially created it will use no snapshot space. At the time data changes on a volume which existed when a snapshot was created the original data will be saved in the associated volume's snapshot reserve space.
As a snapshot is created offline it must be set mountable in order to mount it via an iscsi initiator service.