HP XP External Storage Software - Manual (Page 43)

• If you set a mainframe-system emulation type for the mapped LU, host I/O is always propagated
asynchronously to the external LU regardless of the Cache Mode setting.
• External LU attributes (IO Suppression mode and Cache Mode) set when the LU is mapped cannot
be changed while the LU is mapped. To change these attributes, delete the external LU mapping
(Delete LU operation), and remap the LU with different attributes (Add LU operation).
• External LU attributes for all LDEVs created in an external LU are set to the same values. Those
attributes are modified when the LDEVs are reconfigured using Volume Manager.
• Mapped volumes that have different external volume attributes (IO Suppression mode, Cache
Mode) cannot be used to create one LUSE volume.
• A mapped external LU with IO Suppression mode set to Enable (such as for Flex Copy XP) cannot
be used for the local array's Cache LUN XP operations.
• For a mapped external LU with IO Suppression mode set to Disable (such as for External Storage
XP), Cache LUN XP's Bind mode is not available.
• If you use the mapped external LU for Cache LUN XP operations and set the bind mode, Cache
LUN XP operations require a cache of twice the capacity of the user data.
• For External Storage XP, IO Suppression mode is typically set to Disable. You cannot use a mapped
external LU with IO Suppression mode set to Enable for pair copy operations in Continuous Access
XP, TrueCopy for z/OS®, Continuous Access XP Journal, Universal Replicator for z/OS, Business
Copy XP, ShadowImage for z/OS, or Snapshot XP. Also, the external LU cannot be used for
automatic Auto LUN XP operations.
• Attributes originally set for an external LU on the external array side (such as port security, LUN
security, and Volume Retention Manager attributes) are not kept when the external LU is mapped
as a local array internal LDEV. To keep the original attributes, set those attributes on the mapped
external LU from the local array side.
• If you mapped the external LU and previously set the VMA of LUN Security XP Extension in that
volume, the former VMA setting is superseded when you map the volume again. However, if LUN
Security XP Extension is not installed when you remap the volume, the volume with the VMA setting
cannot be mapped. To change the VMA setting, change it from the local array side.
• Do not combine LDEVs of multiple external volumes to create a LUSE volume. The LDEVs in the
same external volume can only be used to set the LUSE volumes. When you combine LDEVs of
multiple external volumes to create a LUSE volume, you need to consider:
• If a LUSE volume consists of multiple external volumes and one external volume has lower
performance than the other volumes, the lower performance of the volume affects the
performance of the LUSE volume.
• When an external volume which is a component of a LUSE volume is blocked, data reliability
of the LUSE volume will deteriorate because the LUSE volume has both accessible area and
inaccessible area from a host.
• When you disconnect an external volume or resume the use of an external volume, you need
to perform the operation at the same time on all the external volumes which are components
of the LUSE volume.
• Do not update a volume being used or operated by Flex Copy XP. Also do not update the external
LU on the external array side.
• You can delete up to 256 mappings for external LUs at one time.
• Operations cannot be performed if some parts of the local array are blocked. In this case, restore
blocked parts of the local array, and retry the operation.
• When using the Thunder 9500V series subsystem as an external array, the following versions are
recommended. If you use a 9500V array with a version that is earlier than the following versions,
the SATA drive information might not display correctly.
• For Thunder 9530V, Thunder 9520V, Thunder 9570V: version 0658 or later
• For Thunder 9580V, Thunder 9585V: version 1658 or later
External Storage XP user guide for the XP12000, XP10000, SVS200 43