External Storage XP user guide 113
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 the Volume Manager function, you can divide the mapped external LU into a maximum of 256
CVs. However, as they are mapped the LDEVs are used for the OPEN-L emulation type because the Volume
Manager function 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 23 shows the external LU’s maximum
usable capacity for each 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 50 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 51 shows how to determine the volume capacity using the example of the OPEN-3 case.
Table 24 lists the minimum data area capacity, base data area capacity, and control information area
capacity for each emulation type. For the OPEN-L emulation type, CVs cannot be created. Therefore, the
base data area capacity and minimum data area capacity for OPEN-L emulation type are the same. For
the OPEN-V emulation type, the base data area capacity is not listed because there is no concept of the
base data area capacity.
Table 25 lists the base LDEV capacity, minimum LDEV capacity, maximum external LU capacity, and
number of LDEVs that can be defined for the external LU with maximum capacity. For the OPEN-L
emulation type, the base LDEV capacity and the minimum LDEV capacity are the same because CVs
cannot be created. For the OPEN-V emulation type, the base LDEV capacity is not listed because there is
no concept of the base LDEV capacity.
Figure 50 LDEV capacity
Table 23 External LU’s maximum usable capacity
Emulation type External LU’s maximum usable capacity
OPEN-V 2 TB
OPEN emulation type other than OPEN-V 575.98 GB
3380 mainframe emulation type 575.98 GB
3390 mainframe emulation type 695.98 GB
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