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

Chapter 2 66
Disk Devices
When performing disk administration, it is important to understand the
difference between a disk name and a device name.
When a disk is placed under VxVM control, a VM disk is assigned to it.
You can define a symbolic disk name (also known as a disk media name)
to refer to a VM disk for the purposes of administration. A disk name can
be up to 31 characters long. If you do not assign a disk name, it defaults
to disk## if the disk is being added to rootdg (where ## is a sequence
number). Otherwise, the default disk name is groupname##, where
groupname is the name of the disk group to which the disk is added. Your
system may use a device name that differs from the examples.
The device name (sometimes referred to as devname or disk access
name) defines where the disk is located in a system.
NOTE The full pathname of a device is /dev/vx/[r]dsk/devicename. In this
document, only the device name is listed and /dev/vx/[r]dsk is assumed.
Disk Device Naming in VxVM
Prior to VxVM 3.2, all disks were named according to the c#t#d# format.
Fabric mode disks were not supported by VxVM. From VxVM 3.2
onward, there are two different methods of naming disk devices:
• c#t#d# Based Naming Scheme
• Enclosure Based Naming Scheme
c#t#d# Based Naming Scheme
In this naming scheme, all disk devices except fabric mode disks are
named using the c#t#d# format.
The syntax of a device name is c#t#d#, where c# represents a controller
on a host bus adapter, t# is the target controller ID, and d# identifies a
disk on the target controller.