HP XP External Storage Software - Manual (Page 127)

B Required Volume Capacity for
Each Emulation Type
When you map an external volume as a storage system internal volume, you need to specify the
emulation type for the mapped volume. The maximum capacity of an external volume depends on
the specified emulation type.
How to Figure Out Required External Volume Capacity
The capacity required for the LDEV to be mapped 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 39 on page 130.
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) is created in the external volume as you map the volume. When the
capacity of the external volume is more than the base LDEV capacity of the emulation type, the external
volume is divided into multiple LDEVs, each of which have the base LDEV capacity. Because the OPEN-V
emulation type supports 2TB of the volume at the maximum, one LDEV is always created when the
external volume is mapped.
If you use the VLL function, you can divide the mapped external volume into 2,048 CVs at the maximum
as your demand. 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.
When the capacity of the mapped external volume is more than the maximum capacity of the specified
emulation type, a certain part of external volume cannot be used. Table 38 on page 127 shows the
maximum usable capacity of the external volume of each emulation type. For detailed information about
the volume capacity for each emulation type, see Table 40 on page 131.
Table 38 Maximum Usable Capacity of External Volume
Emulation Type Maximum Usable Capacity of External Volume
OPEN-V 2 TB
OPEN emulation type other than OPEN-V 767.99GB (1,610,612,640 blocks)
3380 mainframe emulation type
767.99GB (1,610,612,640 blocks)
3390 mainframe emulation type 927.99GB (1,946,156,940 blocks)
Figure 50 on page 128 shows the relationship of the minimum LDEV capacity, base LDEV capacity,
minimum data area capacity, base data area capacity, and control information area capacity.
XP24000 External Storage Software User’s Guide 127