intro.7 (2010 09)

ManualsBrandsHP ManualsSoftwareHP-UX Manpages

intro(7) intro(7)

NAME

intro - introduction to device special ﬁles

DESCRIPTION

This section describes the device special ﬁles (DSFs) and hardware paths used to access HP peripherals

and device drivers. The names of the entries are generally derived from the type of device being

described (disk, tape, terminal, and so on.), not the names of the device special ﬁles or device drivers

themselves. Characteristics of both the hardware device and the corresponding HP-UX device driver are

discussed where applicable.

Device Types

Devices can be classiﬁed in two device access modes, raw and block . A raw or character-mode device,

such as a line printer, transfers data in an unbuffered stream and uses a character device special ﬁle.

A block-mode device, as the name implies, transfers data in blocks by means of the system’s normal

buffering mechanism. Block devices use block device special ﬁles and may have a character device inter-

face too.

Device File Naming Convention

A device special ﬁle name becomes associated with a device when the ﬁle is created, either automatically

by the special ﬁle daemon

sfd, or explicitly with the insf, mknod,or

mksf command. When creating

device special ﬁles, it is recommended that the following standard naming convention be used:

/dev/subdir/class#[options]

subdir An optional subdirectory for the device class (for example, rdisk for raw device special

ﬁles for disks, disk for block device special ﬁles for disks, rtape for raw tape devices).

class The class of device, such as

tape, disk,orlan.

# The instance number assigned by the operating system to the device. Each class of dev-

ice has its own set of instance numbers, so each combination of class and instance

number refers to exactly one device.

options Further qualiﬁers, such as disk partition (

#), tape density selection for a tape device, or

surface speciﬁcation for magneto-optical media.

Naming conventions for each type of device are described in their respective manpage entries.

Legacy mass storage device special ﬁles have a different naming convention that encodes the hardware

path; this is described in the Device File Types (Mass Storage Devices) section.

Cluster Device Special Files

A cluster device special ﬁle provides a consistent set of device special ﬁles across a set of cluster nodes.

The cluster device special ﬁles of a LUN will be the same on any node in a speciﬁed set of nodes that

share the LUN.

The set of cluster nodes across which cluster device special ﬁles need to be created can be speciﬁed using

the cmsetdsfgroup(1M) command.

The cluster device special ﬁles can be displayed using the io_cdsf_conﬁg(1M) command.

Cluster device special ﬁles are created in both block access mode and raw (character) access mode. Block

mode cluster device special ﬁles are created in the

/dev/cdisk directory, and character mode cluster

device special ﬁles are created in the /dev/rcdisk directory.

Cluster device special ﬁle creation requires that Serviceguard A.11.20 be installed and patched with the

cluster-wide device special ﬁle (cDSF) enhancement, and possibly other dependent patches. See the latest

version of the HP Serviceguard A.11.20 Release Notes for more information.

Hardware Paths

Hardware path information, as well as class names and instance numbers, can be derived from ioscan

output; see ioscan (1M). There are three different types of paths to a device: legacy hardware path , lun-

path hardware path , and LUN hardware path . All three are numeric strings of hardware components,

notated sequentially from the system bus address to the device address. Each number typically

represents the location of a hardware component on the path to the device.

The legacy hardware path is composed of a series of bus-nexus addresses separated by slash (

/) charac-

ters, leading to a host bus adapter (HBA). Beneath the HBA, additional address elements are separated

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (4 pages)

PAGE 1
intro(7) intro(7) NAME intro - introduction to device special files DESCRIPTION This section describes the device special files (DSFs) and hardware paths used to access HP peripherals and device drivers. The names of the entries are generally derived from the type of device being described (disk, tape, terminal, and so on.), not the names of the device special files or device drivers themselves.
PAGE 2
intro(7) intro(7) by period (.) characters. All the elements are represented in decimal. This is the format printed by default by the ioscan command for most devices. An example of a legacy hardware path is 0/0/2/0.1.7.0. The lunpath hardware path is used for mass storage devices, also known as logical units (LUNs). It is identical in format to a legacy hardware path, up to the HBA. Beneath the HBA, additional elements are printed in hexadecimal.
PAGE 3
intro(7) intro(7) Depending on the command, both views may be presented, or the choice of view may be controlled by a command option or an environment variable. For example, the ioscan command shows the legacy view by default, and switches to the agile view if the -N option is specified. EXAMPLES Example 1 The following is an example of a persistent device special file name: /dev/disk/disk3 where disk indicates block disk access and disk3 indicates device class disk and instance number 3.
PAGE 4
(Notes) (Notes) A A 4 Hewlett-Packard Company −1− HP-UX 11i Version 3: September 2010