intro - introduction to device special files
This section describes the device special files used to access HP
peripherals and device drivers. The names of the entries are
generally derived from the type of device being described (disk,
terminal, etc.), 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.
The devices can be classified in two categories, 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.
Block devices, as the name implies, transfer 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 interface too.
A device special file name becomes associated with a device when the
file is created, using the mksf(1M), insf(1M), or mknod(1M) commands.
When creating device special files, it is recommended that the
following standard naming convention be used:
prefix indicates the subdirectory for the device class (for
example, rdsk for raw device special files for disks, dsk
for block device special files for disks, rmt for raw tape
devspec indicates hardware path information and is typically in the
format c#t#d# as follows:
c# Instance number assigned by the operating system
to the interface card. There is no direct
correlation between instance number and physical
t# Target address on a remote bus (for example, SCSI
d# Device unit number at the target address (for
example, SCSI LUN).
options Further qualifiers, such as disk section s# (for backward
compatibility), tape density selection for a tape device, or
surface specification for magneto-optical media.
Hardware path information can be derived from ioscan(1M) output.
Hewlett-Packard Company - 1 - HP-UX Release 11i: November 2000
The following is an example of a disk device special file name:
where dsk indicates block disk access and c0t6d0 indicates disk access
at interface card instance 0, target address 6, and unit 0. Absence
of s# indicates access to the entire disk (see disk(7) for details).
The following is an example of a tape device special file name:
where rmt indicates raw magnetic tape, c2 indicates that the device is
connected to interface card instance 2, t3 indicates that target
device address is set to 3, d0 indicates that the tape transport
resides at unit address 0, and QIC150 identifies the tape format as
QIC150 (see mt(7) for details).
In the past, other naming conventions have been used for device
special files. Using ln(1) to create a link between the old and new
standard name is useful as a temporary expedient until all programs
using an old naming convention have been converted.
ioscan(1M), mksf(1M), insf(1M), lssf(1M), hier(5), introduction(9).
The system administrator manual for your system.
Web access to HP-UX documentation at http://docs.hp.com.
Hewlett-Packard Company - 2 - HP-UX Release 11i: November 2000