Information Technology Reference
In-Depth Information
This identifies a device attached to the
sbus
with a main system bus address
of
1f,0
; an
esp
device (SCSI bus) attached at SBus slot
0
, offset
4000
; and an
sd
device (SCSI disk) with a SCSI bus target of
3
, a logical unit of
0
, and an
argument of
a
, which represents slice
a
of the disk.
These full device pathnames are located under the
/devices
directory and
are referred to as physical device names. Although these physical names
define the exact location of devices within the system, they are difficult to
remember and use, and usually are not directly used.
Logical Device Names
Another naming convention that is easier to use is logical device names.
Logical device names are used to identify disk, tape, and CD-ROM devices
and provide either
raw access
(one character at a time) or
block access
(via a
buffer for accessing large blocks of data).
All logical device names reside under the
/dev
directory, and the
dsk
subdi-
rectory identifies the device as a block disk device (the
rdsk
subdirectory
indicates a raw disk device).
The logical name of SCSI disk devices on a SPARC system identifies the
SCSI controller (bus), SCSI target (location on bus), drive (almost always 0),
and slice (partition), as shown in the following logical device name:
/dev/dsk/c0t3d0s4
This block disk device is addressed as SCSI controller
0
, SCSI bus target
3
,
drive
0
, and slice (partition)
4
. Note the similarities (and differences) between
this logical device name and its physical device name, as described in the pre-
vious section. Devices that have direct controllers as opposed to bus-oriented
controllers (such as IDE drives) do not include the
t#
(bus target) portion of
the logical device name.
Some commands require using raw (character) device names (
/dev/rdsk/*
).
These include
format(1M)
, used to format a disk,
newfs(1M)
, used to create a
file system, and
fsck(1M)
, used to check a file system. Other commands
require using block device names (
/dev/dsk
). These include
mount(1M)
, used
to make a file system available, and
df(1M)
, used to display free file system
space. A few commands, such as
prtvtoc(1M)
, accept either raw or block log-
ical device names.
Of the three types of disk device names used in the Solaris environment, logical
devices names are used most frequently.
