HP StorageWorks XP Remote Web Console Software - Manual (Page 13)

LUN Security XP Extension user guide 13
with logical volume B, LUN Security XP Extension requires license capacity for both logical volumes A and
B. Therefore, LUN Security XP Extension needs 4 GB of license capacity.
Figure 2 Calculating license capacity (when VMA is set)
NOTE: If you do not change the logical volumes’ default access attribute, which is Read/Write, you do
not need extra license capacity. For example, in Figure 2 , if you set VMA on logical volumes A and B
when they do not form a pair, 2 GB of license capacity is enough. However, in Figure 2 , VMA is set on
logical volume A and logical volume A’s access attribute is changed to Read Only. Since logical volumes
A and B form a pair, in Figure 2 , you need 4 GB of license capacity.
When setting VMA and the access attribute to a logical volume that is not specified as the logical volume
of a pair, and then creating a pair using that logical volume, you need enough license capacity for both
logical volumes forming the pair. Therefore, if LUN Security XP Extension’s license capacity is insufficient,
you cannot create a pair even if the local array copy software’s license capacity is sufficient. Figure 3
shows an example of this case.
Figure 3 Example of when you cannot create a pair
Calculating license capacity when VMA and extent are set
When creating pairs using volumes with extents, LUN Security XP Extension’s required license capacity
depends on the access attribute settings. You can set multiple extents in one volume. If the volume you use
to create a pair contains a Read Only extent, the whole volume’s license capacity is required.
This section describes how to calculate the required license capacity when specifying volume A (whole
capacity is 10 GB, and VMA and 3 GB of Read Only extent are set) as the P-VOL to create a pair.
NOTE: You can set extents only in volumes with VMAs. If the P-VOL has VMA, the S-VOL also needs
VMA. But for extents, there is no problem, even if the S-VOL does not have any extents. The P-VOL’s extents
are copied to the S-VOL when creating a pair.