HP StorageWorks XP Remote Web Console Software - Manual (Page 16)

P-VOL
S-VOL
6
S-VOL
5
S-VOL
4
S-VOL
8
S-VOL
7
S-VOL
1 MU#=0
MU#=1
MU#=1
MU#=2
MU#=1
MU#=2
MU#=1
MU#=2
S-VOL
2
S-VOL
3
MU#=2
S-VOL
9
Legend
: Root Volume : Node Volume
: Leaf Volume
: L1 pair
: L2 pair
Figure 2 Cascade Pairs
The first cascade layer (L1) is the original 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 on page 16, this layering scheme allows you to create up to nine copies (S-VOLs) of one
Business Copy P-VOL. MU# in Figure 2 on page 16 refers to the MU number, which identifies each
MU. For example, MU# = 1 under the S-VOL1 means that the MU number of the P-VOL that pairs
with the S-VOL1 is 1.
Note: Combination of L1 and L2 pairs with the Continuous Access volumes is allowed; however, node
volumes and leaf volumes are both considered secondary volumes (S-VOLs) by Continuous Access.
When you create a new volume pair, the initial copy starts and all the data in the P-VOL is copied to
the S-VOL. Figure 3 on page 17 shows the change of the status of a pair from the start to the end
of the initial copy operation.
About Business Copy Operations 16