B required volume capacity for each emulation type, Determining required external volume capacity, Required volume capacity for each emulation – HP XP External Storage Software User Manual
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B Required 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. The maximum capacity of an external volume depends on the specified
emulation type.
Determining 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
•
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 has the base LDEV capacity.
Because the OPEN-V emulation type supports 4 TB 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.
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 60 Maximum Usable Capacity of an External Volume
Maximum Usable Capacity of External Volume
Emulation Type
4 TB
OPEN-V
767.99 GB (1,610,612,640 blocks)
OPEN emulation type other than OPEN-V
767.99 GB (1,610,612,640 blocks)
3380 mainframe emulation type
927.99 GB (1,946,156,940 blocks)
3390 mainframe emulation type
“Idea of LDEV Capacity” (page 153)
shows the relationship of the minimum LDEV capacity, base
LDEV capacity, minimum data area capacity, base data area capacity, and control information
area capacity.
shows how to figure out the volume capacity using OPEN-3.
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Required Volume Capacity for Each Emulation Type