HP StorageWorks XP Remote Web Console Software - Manual (Page 32)

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If you map an external LU that is equal to or greater than 695.98 GB with a 3390 mainframe
emulation type, you can access data stored in the field up to 695.98 GB. You cannot access
data stored in the field over 695.98 GB.
However, for emulation types with a small base capacity, some of the field of 695.98 GB
might not be available. For more information, see
“Required volume capacity for emulation
types” (page 160) .
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If you plan to use the mapped external LU from the mainframe OS (volume is mapped with a
3380-x or 3390-x mainframe emulation type), you must select an external LU that consists of
one LDEV or you must first adjust the capacity of the external LU to be mapped. If multiple
LDEVs exist in one external LU and if numerous I/Os are made to these LDEVs, the read and
write commands might time-out. When the commands time-out, the SIM (21D2xx) is reported.
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When mapping an external LU as internal LDEVs with emulation types other than OPEN-V,
the number of volumes and the volume capacity of the mapped internal LDEVs depends on
the original external LU's capacity and each emulation type's normal size. When mapping
an external LU using emulation types other than OPEN-V, an XP array management information
area is required in the mapped LU. This means that the capacity available after mapping is
slightly smaller than the actual external LU capacity. Available capacity decreases by the size
of the XP array management information area, and all prior data must be considered lost. For
more information, see the HP Flex Copy XP user guide.
Figure 12 (page 32) shows an example where the external LU's original capacity is larger
than (or a multiple of) the normal size of the local array's emulation type (OPEN-3 in this
example). Therefore, in this example, the local array can realize two fully-sized OPEN-3 LDEVs,
with some space (insufficient to create a full OPEN-3) left over.
Figure 12 External LU capacity is larger than the specified emulation type's basic capacity
(OPEN-3 example)
32 Preparing for XP External Storage operations