VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Introduction
86 VERITAS Volume Manager Administrator’s Guide
VxVM usesDMP metanodesto accessdisk devicesconnected 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 MultiplePhysical Pathsto aDisk asone Metanode”
on page 86 for an illustration of how DMP sets up a metanode for a disk in a supported
disk array.
How DMP Represents Multiple Physical Paths to a Disk as one Metanode
As described in “Enclosure-Based Naming” on page 5, 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 Enclosure in a SAN Environment” on
page 87, shows that two paths, c1t99d0 and c2t99d0, exist to a single disk in the
enclosure, but VxVM uses the single DMP metanode, enc0_0, to access it.
Single DMP
Metanode
Multiple
Paths
DMP
VxVM
Mapped by DMP
Multiple
Paths
Host
Disk
c2c1