3-10 Preparing for Universal Volume Manager Operations
Hitachi Universal Storage Platform V/VM Universal Volume Manager User’s Guide
• When you use the mapped external volume from the mainframe OS, set
the MIH (Missing Interrupt Handler) timer to 45 seconds (which is the
recommended value).
Volume Attribute Guidelines
• The external volume attributes for all the LDEVs created in an external
volume become the same. The attributes are taken over, when the LDEVs
are reconfigured using the VLL function.

• The Cache Mode becomes the same for all the LDEVs in one external

volume.
• The attributes that are set for the external volume originally on the
external storage system side (such as the port security, the LUN security,
the Volume Retention Manager attributes, and so on) are not kept, when
the external volume is mapped as an internal volume. If the original
attributes are required to be set, set the attributes on the mapped external
volume from the local storage system side.
• For the external volume, for which the Cache Mode is set to Disable, the
bind mode for the Cache Residency Manager operation is not available.
• If you use the mapped external volume for the Cache Residency Manager
operation and set the bind mode, the cache of twice as much capacity as
the user data is required for the Cache Residency Manager operation.
Creating LUSE Volume Guidelines
• 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.
• The mapped volumes that have different cache mode settings cannot be
used to create one LUSE volume.