B required volume capacity for each emulation type, 38 maximum usable capacity of external volume, Required volume capacity for each emulation type – HP XP External Storage Software User 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