About Universal Volume Manager Operations 2-11
Hitachi Universal Storage Platform V/VM Universal Volume Manager User’s Guide
• CLPR
When the cache memory is partitioned using Virtual Partition Manager,
configure a cache logical partition (CLPR) to access the mapped volume.
See the Virtual Partition Manager User’s Guide for the detailed information
on CLPR.
Cross-subsystem Paths
A cross-subsystem path is a route from a local storage system port to an
external storage system port. To prepare for possible failures of the cable, the
switch, or the channel processor, it is recommended that you create redundant
cross-subsystem paths. This redundancy allows you to continue performing
the I/O operations to the external volumes when you maintain the cable. You
can set up to eight paths.
A group of redundant cross-subsystem paths is called a "path group". In a
path group, the cross-subsystem path that has the highest priority is called
the primary path. The cross-subsystem paths other than priority path are
called alternate paths.
• Setting of the path groups
A path group is automatically set when you map the external volume. You
cannot set a new path group by itself.
• Setting of cross-subsystem paths
Use fibre cables to establish multiple paths between the external storage
system and the local storage system. At this time, connect to the external
storage system from the different cluster port of the local storage system.
If multiple paths are established between the two storage systems, the
starting points of the paths (i.e., external ports of the local storage system)
and the ending points (i.e., WWNs showing the ports of the external
storage system) will be displayed in a dialog box when you map an
external volume. In this dialog box, you can set cross-subsystem paths by
selecting the starting points and the ending points of the paths according
to the actual cable connections.
• Setting of redundant cross-subsystem paths
You can set redundant cross-subsystem paths (add alternate paths) when
you set the cross-subsystem paths. You can also add an alternate path or
change the priority after completing the mapping of the external volume.

Path Mode

Path mode is either Single mode or Multi mode, depending on the connected
external storage system.