HP StorageWorks External Storage XP user guide for the XP12000, XP10000, SVS200 (T1706-96009, October 2007)

• 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
inoneexternalLUandifnumerousI/OsaremadetotheseLDEVs,thereadandwritecommands
might timeout. When the commands timeout, the SIM (21D2xx) is reported.
• 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 StorageWorks Flex Copy XP user guide.
Figure 12 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 Ext. LU cap. is larger than the spec. emulation type's basic cap. (OPEN-3
ex.)
Figure 13 shows an example where the external LU's original capacity is smaller than the normal
size of the local array's emulation type. In this example, since the resulting space is insufficient to
create a local array OPEN-3 LDEV, you can designate it as either a local array OPEN-V or an
OPEN-3 CVS LDEV. If the external LU were an XP of OPEN-3 emulation type, forfeiting a small amount
of management space would also result in an OPEN-3 CVS volume or an OPEN-V.
Figure 13 External LU capacity is smaller than the specified emulation type's basic
capacity
• IO Suppression mode can only be selected when the volume being mapped is set to the OPEN-V
emulation type. If a different emulation type is set, IO Suppression mode is automatically set
to Disable.
38
Preparing for External Storage XP operations