VERITAS Volume Manager 3.1 Administrator's Guide

Disk Tasks
Disk Devices
Chapter 4148
Disk Devices
Two classes of disk devices can be used with the Volume Manager:
standard devices and special devices. In Volume Manager, special devices
are considered physical disks connected to the system that are
represented metadevices with one or more physical access paths. The
access paths depend on whether the disk is a single disk or part of a
multiported disk array connected to the system. Use the vxdisk utility
to display the paths of a metadevice, and to display the status of each
path (for example, enabled or disabled).
NOTE Using special devices applies only to systems with the Dynamic
Multipathing (DMP) feature.
When performing disk administration, it is important that you recognize
the difference between a device name and a disk name.
The device name (sometimes referred to as devname or disk access
name) is the location of the disk. The syntax of a typical device name is
c # t # d # , where:
• c # —The number of the controller to which the disk drive is attached
(used on HP-UX systems)
• t # and d # —The target ID and device number that constitute the
address of the disk drive on the controller (used on HP-UX systems)
• s2 —The HP-UX partition number on the boot disk drive (used on
HP-UX 11i Version 1.5 systems)
On HP-UX 11i Version 1.5 systems, the HP-UX partition number on the
boot disk drive is c # t # d # s2, where s2 is the slice or partition number.
A VM disk has two regions:
• private region —a small area where configuration information is
stored. A disk label and configuration records are stored here.
• public region —an area that covers the remainder of the disk and is
used to store subdisks (and allocate storage space).
Three basic disk types are used by Volume Manager: