HP StorageWorks XP Remote Web Console Software - Manual (Page 34)

If you format the external array's mapped LU from the external array side, data that existed
prior to formatting cannot be ensured. When using the mapped external LU from the mainframe
OS, format the mapped volume from the local array side.
•
IO Suppression mode is set when the LU is mapped and it cannot be changed while the LU
is mapped. To change IO Suppression mode, 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.
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A mapped external LU with IO Suppression mode set to Enable (such as for XP Flex Copy)
cannot be used for the local array's XP Cache LUN operations.
•
For a external LU with IO Suppression mode set to Disable (such as for XP External Storage),
XP Cache LUN's Bind mode is not available.
•
If you use the mapped external LU for XP Cache LUN operations and set the bind mode, XP
Cache LUN operations require a cache of twice the capacity of the user data.
•
For XP External Storage, 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 XP
Continuous Access, Hitachi TrueCopy™ for z/OS, XP Continuous Access Journal, Hitachi
Universal Replicator™ for z/OS, XP Business Copy, Hitachi ShadowImage™ for z/OS, or
XP Snapshot. Also, the external LU cannot be used for automatic XP Auto LUN operations.
•
Attributes originally set for an external LU on the external array side (such as port security, HP
XP Secure Manager, 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 map an external LU for which the VMA of Data Retention Utility is set, you need to
configure system options before performing the Discovery operation to enable the VMA
information. Call HP technical support to ask about how to configure system options.
•
If you mapped the external LU and previously set the VMA of Data Retention Utility in that
volume, the former VMA setting is superseded when you map the volume again. However, if
Data Retention Utility 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 XP Flex Copy. 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.
34 Preparing for XP External Storage operations