HP StorageWorks XP Remote Web Console Software - Manual (Page 160)

B Required volume capacity for emulation types
When mapping an external LU as a local array internal LDEV, you must specify the mapped
volume's emulation type.
How to determine the required external volume capacity
The capacity required for the LDEV to be mapped is the total capacity of the data area for storing
actual user data and the control information area for storing 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 the data area for Customized Volume (CV) (called minimum data area capacity) also depends
on the emulation type.
Use the following equation to calculate the minimum capacity required for an LDEV (minimum LDEV
capacity) for each emulation type:
Minimum LDEV capacity = Minimum data area capacity + control information area capacity
If the external LU's capacity is less than this minimum LDEV capacity, the emulation type cannot
be specified.
Use the following equation to calculate the base LDEV capacity for each emulation type:
Base LDEV capacity = Base data area capacity + Control information area capacity
When the external LU's capacity is less than the emulation type's base LDEV capacity, one CV is
created in the external LU as you map the volume. When the external LU's capacity is more than
the emulation type's base LDEV capacity, the external LU is divided into multiple LDEVs, each
having the base LDEV capacity. Because the OPEN-V emulation type supports a maximum of 2TB
of the volume, one LDEV is always created when the external LU is mapped.
If you use Volume Manager, you can divide the mapped external LU into a maximum of 256 CVs.
However, LDEVs as they are mapped are used for the OPEN-L emulation type because Volume
Manager is not applicable to the OPEN-L emulation type.
The following restrictions apply for the external LU's maximum usable capacity:
•
The external LU can be divided into a maximum of 256 CVs. Therefore, the external LU's
maximum capacity must meet the following equation:
Maximum usable capacity of the external LU Base LDEV capacity × 256
•
Each emulation type has its own maximum usable capacity. Table 34 (page 160) shows the
external LU's maximum usable capacity for each emulation type.
Table 34 External LU's maximum usable capacity
External LU's maximum usable capacity Emulation type
2 TB OPEN-V
575.98 GB OPEN emulation type other than OPEN-V
575.98 GB 3380 mainframe emulation type
695.98 GB 3390 mainframe emulation type
According to these restrictions, you can determine the external LU's maximum usable capacity for
each emulation type. When the mapped external LU's capacity is more than the maximum capacity
of the specified emulation type, a certain part of the external LU cannot be used.
Figure 70 (page 161) shows the relationship of the minimum LDEV capacity, base LDEV capacity,
minimum data area capacity, base data area capacity, and control information area capacity.
160 Required volume capacity for emulation types