HP StorageWorks XP24000/XP20000 Business Copy Software User Guide (T5213-96034, May 2011)

Figure 2 Cascade Pairs
The first cascade layer (L1) is the original XP Business Copy pair. In case of cascaded pairs, the
P-VOL of the L1 pair is called root volume, and the S-VOL is called node volume. The P-VOL of the
second cascade layer (L2) is the node volume of L1 pair, and the S-VOL of the L2 pair is called
leaf volume. As shown in Figure 2 (page 11), this layering scheme allows you to create up to nine
XP Business Copy Operations 11