Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

DMP coexistence with HP-UX native multipathing
The HP-UX 11i v3 release includes support for native multipathing, which can
coexist with DMP. HP-UX native multipathing creates a persistent (agile) device
in the /dev/disk and /dev/rdisk directories for each disk that can be accessed
by one or more physical paths. To maintain backward compatibility, HP-UX also
creates legacy devices in the /dev/dsk and /dev/rdsk directories.
VxVM recreates disk devices for all paths in the operating system’s hardware
device tree as DMP nodes in the /dev/vx/dmp and /dev/vx/rdmp directories,
independently of the devices that are listed in the /dev/dsk and /dev/rdsk
directories. VxVM uses a DMP node to represent a disk that can be accessed by
one or more physical paths. DMP nodes are not used by the native multipathing
feature of HP-UX.
VxVM commands display device names according the naming scheme that has
been selected.
See “Changing the disk-naming scheme” on page 98.
By default, VxVM is configured to use DMP metanodes. If you want to use HP-UX
native multipathing, you must add the HP-UX native multipathing metanodes as
foreign devices.
See “Foreign devices” on page 96.
See “Migrating between DMP and HP-UX native multipathing” on page 143.
For more information on administering native multipathing with Base-VxVM and
VxVM-Full, see the Veritas Volume Manager Release Notes.
Migrating between DMP and HP-UX native multipathing
Note: Migrating from one multipath driver to the other overwrites the existing
PFTO settings for the migrating device. It will take the default PFTO setting for
the mutipath driver that it is migrated to.
You can use the vxddladm addforeign and vxddladm rmforeign commands to
migrate a system between DMP and HP-UX native multipathing. These procedures
migrate devices in the /dev/disk and /dev/rdisk directories.
Note: Before migrating between DMP and HP-UX native multipathing, ensure that
no applications are accessing VxVM volumes. Migration is not supported without
first stopping any applications that are using the volumes.
143Administering Dynamic Multipathing
How DMP works