VERITAS Volume Manager 3.5 Administrator's Guide (September 2004)

Administering Dynamic Multipathing (DMP)
Introduction
Chapter 3 107
separate group of LUNs. If a single LUN in the primary controller’s
LUN group fails, all LUNs in that group fail over to the secondary
controller’s passive LUN group.
VxVM uses DMP metanodes to access disk devices connected to the
system. For each disk in a supported array, DMP maps one metanode to
the set of paths that are connected to the disk. Additionally, DMP
associates the appropriate multipathing policy for the disk array with
the metanode. For disks in an unsupported array, DMP maps a separate
metanode to each path that is connected to a disk.
See the figure “How DMP Represents Multiple Physical Paths to a Disk
as one Metanode,” for an illustration of how DMP sets up a metanode for
a disk in a supported disk array.
Figure 3-1 How DMP Represents Multiple Physical Paths to a Disk as one
Metanode
As described in “Enclosure-Based Naming” on page 7, VxVM implements
a disk device naming scheme that allows you to easily recognize to which
array a disk belongs. The figure, “Example of Multipathing for a Disk
Single DMP
Metanode
Multiple
Paths
DMP
VxVM
Mapped by DMP
Multiple
Paths
Host
Disk
c2c1