HP XP P9500 Storage - Manual (Page 84)

B Required external volume capacity for each emulation
type
When you map an external volume as an internal volume, you need to specify the emulation type
for the mapped volume. This appendix describes required external volume capacity corresponding
to the specified emulation type.
Determining required external volume capacity
The capacity required for the external volume to be mapped is the total capacity of LDEVs created
in the external volume. The capacity required for the LDEV is the total capacity of the data area
for storing the actual user data and the control information area for storing the control information.
The capacity of the data area (called base data area capacity) and the capacity of the control
information area (called control information area capacity) depend on the emulation type. The
minimum capacity of data area for Custom-sized Volume (CV) (called minimum data area capacity)
also depends on the emulation type. For detailed information about the LDEV capacity for each
emulation type, see
Table 35 (page 86) .
•
You can calculate the minimum capacity required for an LDEV (minimum LDEV capacity) for
each emulation type using the following equation:
Minimum LDEV capacity = Minimum data area capacity + control
information area capacity
If the capacity of the external volume is less than this minimum LDEV capacity, the emulation
type cannot be specified.
•
You can calculate the base LDEV capacity for each emulation type using the following equation:
Base LDEV capacity = Base data area capacity + Control information
area capacity
When the capacity of the external volume is less than the base LDEV capacity of the emulation
type, one Custom-sized Volume (CV) of the maximum capacity which can be created in the external
volume is created as you map the volume. When the capacity of the external volume is more than
the base LDEV capacity of the emulation type, multiple LDEVs, each of which has the base LDEV
capacity, are created in the external volume as you map the volume.
If you use the VLL function, you can create 2,048 CVs at the maximum as your demand in the
mapped external volume. However, the LDEVs as they are mapped are used for the OPEN-L
emulation type, because the VLL function is not applicable to the OPEN-L emulation type.
Figure 25 (page 85) shows the relationship of the minimum LDEV capacity, base LDEV capacity,
minimum data area capacity, base data area capacity, and control information area capacity.
Figure 26 (page 85) shows how to figure out the capacity required for the external volume using
the example of the OPEN-3 case.
84 Required external volume capacity for each emulation type