HP-UX System Administrator's Guide: Overview HP-UX 11i v3 (B3921-90011, September 2010)

The following directories still exist in HP-UX 11i version 3 for backwards compatibility. They
contain the legacy device special files defining the physical drives on a server (the legacy form):
/dev/dsk
Contains legacy device special files for block mode access to physical disk devices
on a server.
/dev/rdsk
Contains legacy device special files for character mode access to physical disk
devices on a server.
Within these directories, files have names in the format “c#t#d#” (where c# represents the
controller instance number, t# represents the SCSI target number, and d# represents the SCSI
LUN number).
Examples:
/dev/dsk/c3t7d0
/dev/rdsk/c3t15d5
With legacy device special files that are associated with disks an optional part of the filename
can represent disk partition numbers. By convention, in the absence of this optional part of the
device file name the name represents an entire disk. This optional part expands the format of
the name to be c#t#d#s# (where s# represents the partition number, tape density, or other
information).
Examples:
/dev/dsk/c3t7d0s3
/dev/rdsk/c3t15d7s1
NOTE: You can use both legacy and persistent device special files simultaneously but to gain
the many benefits of persistent device special files, you need to use those.
For example, using legacy device special files you can only define and address up to 256 external
buses on a server. If you have more than 256 you will need to use persistent device special files
to access the devices beyond the 256 address boundary.
For Additional Information on Naming Device Special Files
Additional information on naming device special files is located in the following manpages:
• autochanger(7)
• disk(7)
• intro(7)
• mt(7)
Mass Storage Hardware Paths (three formats)
Hardware paths, as the name implies, define the physical paths that data travels to reach devices.
In HP-UX 11i version 3 there are three formats to specific hardware paths to mass storage devices.
Legacy Hardware Paths
This is the format used in releases prior to HP-UX 11i Version 3. It is composed of a series of
bus-nexus addresses separated by slash characters (“/”) leading to the host bus adapter (HBA);
beneath the HBA, additional address elements are separated by periods (“.”).
For directly connected devices, the addressing can be a simple target and LUN:
0/0/2/0.1.7.0
For SCSI-3 devices connected through a storage area network (SAN), legacy addressing is
emulated with a domain, area, port, virtual bus, virtual target, and virtual LUN:
0/2/1/0.1.5.0.0.3.7
56 Major Components of HP-UX