HP StorageWorks External Storage XP user guide (December 2005)

82 External Storage XP for the XP10000/XP12000
Figure 44 shows how to calculate the LU capacity for OPEN-3 emulation. For open systems, the most used
emulation type is OPEN-V.
Figure 44 Calculating LU capacity (OPEN-3 example)
Each emulation type has certain minimum and maximum capacities (see Table 14 on page 84):
• Base LDEV capacity (4,818,240 in the OPEN-3 example). When the external LU’s capacity is less than
the emulation type’s base LDEV capacity, a Customized Volume (CV) is created when mapping the
volume. When the external LU’s capacity is more than the XP10000/XP12000 emulation type’s base
LDEV capacity, the external LU is divided into multiple LDEVs, each having the base capacity. Because
the OPEN-V emulation type supports a maximum of 2 TB of the volume, one LDEV is always created
when the external volume is mapped.
• The maximum number of LDEVs created when the maximum capacity of an external LU is mapped (256
in the OPEN-3 example). If you use the CVS function within the XP10000/XP12000, you can further
divide an XP10000/XP12000 VDEV mapped to an external LU into a maximum of 256 smaller LDEVs
of a particular emulation type (except for OPEN-L and OPEN-M, which cannot be used with CVS).
The following restrictions apply to the external volume’s maximum usable capacity:
• The external volume can be divided into a maximum of 256 CVs and, therefore, the external volume’s
maximum capacity must meet the following equation:
Maximum usable capacity of the external volume ≤Base LDEV capacity × 256
• Each emulation type has its own maximum usable capacity. Table 12 shows the maximum usable
capacity of the external volume for each emulation type.
Table 12 External volume’s maximum usable capacity
Emulation type External volume’s maximum usable capacity
OPEN-V 2 TB
OPEN emulation type other than OPEN-V 575.98 GB
3380 mainframe emulation type 575.98 GB
3390 mainframe emulation type 695.98 GB