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).
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 | NOTE: Using special devices applies only to systems with the
Dynamic Multipathing (DMP) feature. |
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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:
sliced—the public and private regions are on different
disk partitions.
simple—the public and private regions are on the
same disk area (with the public area following the private area).
nopriv—there is no private region (only a public
region for allocating subdisks).
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| NOTE: For HP-UX 11i, disks (except the root disk) are treated
and accessed as entire physical disks, so a device name of the form c#t#d# is used. On HP-UX 11i Version 1.5, the root disk
is on partition 2, c#t#d#s2. |
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The full pathname of a device is /dev/vx/dmp/devicename. In this document, only the device name is listed
and /dev/vx/dmp is assumed.
The disk name (sometimes referred to
as disk media name) is an administrative
name for the disk, such as disk01. If you do not assign a disk name, the disk name
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.
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