Viewing the System Configuration with ioscan

The /usr/sbin/ioscan command is the single most versatile tool in HP-UX for displaying your system configuration. For example, you can use ioscan to identify available hardware addresses.

Terse Listing of ioscan

In its simplest form, /usr/sbin/ioscan displays hardware path, device class, and description. The -u (usable devices) or -k (kernel structures) options give fastest response, because they do not probe the hardware.

The following example shows devices on a Series 800 Model E, connected through the HP-PB bus converter at address 56. The 56/52 is the address of the single-ended SCSI interface. The shaded digits below are the addresses already being used on the card. Note that there is no 56/52.4.0. If you attach another SCSI device to this card, you can set its address to 4.

/usr/sbin/ioscan -k
H/W Path   Class               Description
==========================================
56         bc                  Bus Converter
56/52          ext_bus         HP 28655A - SCSI Interface
56/52.0           target
56/52.0.0            tape      SCSI Tape
56/52.1           target
56/52.1.0            disk      HP C2247M1 - SCSI Disk
56/52.2           target
56/52.2.0            disk      HP C2247M1 - SCSI Disk
56/52.3           target
56/52.3.0            disk      TEAC FC-1 ... - SCSI Disk
56/52.5           target
56/52.5.0            disk      HP C2247M1 - SCSI Disk
56/52.6           target
56/52.6.0            disk      HP C2247M1 - SCSI Disk...

Understanding Hardware Addresses

You can identify each piece of hardware configured to an HP-UX computer by its hardware address (shown in ioscan as H/W Path).

The length of these numerical sequences differ by system model and architecture, but every hardware path leads you through the bus structure, starting from the bus closest to the system processor and ending at the output device.

ioscan -H hardware_path shows you the sequence of connection to or from the specified location. In the following example,, which displays output from a Model 770, a disk attached to the GSC built-in Fast/Wide SCSI Interface has the hardware address 8/0.5.0.

/usr/sbin/ioscan -H 8/0.5.0
H/W Path       Class                     Description
====================================================
               bc
8              bc                       I/O Adapter
8/0                ext_bus              GSC built-in Fast/Wide SCSI Interface
8/0.5                 target
8/0.5.0                  disk            DEC     DSP3210SW

The hardware path can be decoded as follows:

8: identifies the bus adapter connecting the GSC+ bus to the system bus.
0: identifies the slot number of the Fast/Wide SCSI interface. (See Figure B-3 in Appendix B, Bus Architectures.)
5: represents the "target", or SCSI address, set on the disk device itself.
0: indicates a unit number or SCSI LUN number.

Field separators (slash (/) or dot (.)) separate the numbers of the hardware address and have no bearing on system administration. The displayed classes are more meaningful in the context of instance numbers, which are visible in ioscan -f listings, and will be discussed shortly. Explanation of hardware addresses on multi-function cards is in Appendix B.

Understanding the Description in ioscan

The description field displayed by ioscan derives from the peripheral device itself, and is sometimes more cryptic than is ideal. Typically, a numeric description refers to the manufacturer's vendor ID, and in some cases, this number corresponds to more than one model number. If you are troubleshooting a peripherals problem, the description is often useful information to an HP support engineer.

Full Listing of ioscan

ioscan -f displays full information about the system configuration, including instance number, device/interface driver, software state, and hardware type. The -fn option displays the device special files also.

/usr/sbin/ioscan -f 
Class       I  H/W Path     Driver     S/W State H/W Type    Description
========================================================================
...
ext_bus     0  8/0          c720        CLAIMED  INTERFACE   F/W SCSI
target      0  8/0.5        tgt         CLAIMED  DEVICE
disk        0  8/0.5.0      sdisk       CLAIMED  DEVICE      HP      C2247
ba          0  8/12         bus_adapter CLAIMED  BUS_NEXUS   Core I/O Adapter
ext_bus     2  8/12/0       CentIf      CLAIMED  INTERFACE   Parallel Interface
audio       0  8/12/1       audio       CLAIMED  INTERFACE   Audio
tty         0  8/12/4       asio0       CLAIMED  INTERFACE   RS-232C
ext_bus     1  8/12/5       c700        CLAIMED  INTERFACE   SCSI
target      1  8/12/5.0     tgt         CLAIMED  DEVICE
disk        1  8/12/5.0.0   sflop       CLAIMED  DEVICE      TEAC    FC-1
...
lan         0  8/12/6       lan2        CLAIMED  INTERFACE   LAN
bc          2  10           ccio        CLAIMED  BUS_NEXUS   I/O Adapter
graphics    0  10/0         graph3      CLAIMED  INTERFACE   Graphics
...

Understanding Class and Instance

The following ioscan output shows just the ext_bus class of a sample Model 770 system. The card instance numbers are listed under I and are highlighted.

For device file naming and hardware mapping, the only significant instance numbers are those associated with the INTERFACE hardware type.

/usr/sbin/ioscan -C ext_bus -f 
Class     I  H/W Path  Driver      S/W State H/W Type  Description
=====================================================================
ext_bus   0  8/0        c720       CLAIMED  INTERFACE   F/W SCSI
ext_bus   2  8/12/0     CentIf     CLAIMED  INTERFACE   Parallel Interface
ext_bus   1  8/12/5     c700       CLAIMED  INTERFACE   SCSI

The card instance number is assigned by the operating system to the interface card and reflects the order ioconfig binds that class of interface card to its driver when it boots.

Instance is stored in two files — /etc/ioconfig and /stand/ioconfig. These files retain their information across reboots, unless one is corrupted or missing, in which case, ioinit will rebuild the entire /dev structure. (If this occurs, you would have to recreate any customized permissions or files.)

For further explanation of card instance, read the white paper entitled HP-UX 10.0 Device File Naming Convention.

An Example Showing Correlation Between Card Instance and Device Files

The following example shows ioscan output taken from a Model 735. The shaded numbers show how card instance number and hardware path elements map directly into the device special file /dev/dsk/c1t5d0 as card instance, target number, and device number.

Typically, the card instance maps as the digit after the letter c (or for terminals, the number after tty), as shown in the following example.

Note, the card instance designated in the device special file refers to the interface card, not to the instance number of the peripheral device attached to the card. (Ignore those numbers. This is a departure from the LU concept of previous HP-UX Series 800 releases. LU numbers were similar to device instance numbers and are not used.)

The card instance number is unique only for the specific class (in this case, ext_bus) of interface. Thus, for example, the tty class of interface has its own sequence of card instance numbers, beginning with zero, which appear in its device files.

/usr/sbin/ioscan -fn -H 2/0/7 
Class       I  H/W Path   Driver      S/W State   H/W Type     Description
===========================================================================
ext_bus     1  2/0/7      c700        CLAIMED     INTERFACE    Built-in F/W SCSI
target      3  2/0/7.5    target      CLAIMED     DEVICE
disk        2  2/0/7.5.0  sdisk       CLAIMED     DEVICE       HP      C2247
                    /dev/dsk/c1t5d0   /dev/rdsk/c1t5d0
...

Identifying Device Special Files Associated with a Peripheral Device

You can use ioscan -fn (or -fkn or -fun) to show device special file names associated with a peripheral. You can also add other ioscan options (such as -H, -C, -d, or -I) to limit your output to specific elements in your configuration.

The following example, using -C tape, shows the device files available for tape class, as well as the location and type of tape device. Note too, the new tape device file naming convention. These are explained in Chapter 6, "Configuring Tape Drives," and on the mt(7) manpage.

/usr/sbin/ioscan -fn -C tape
Class   I  H/W Path   Driver S/W State H/W Type  Description
============================================================
tape    0  56/52.0.0  tape2  CLAIMED   DEVICE    WANGTEK 51000  SCSI
                     /dev/diag/rmt/c0t0d0   /dev/rmt/c0t0d0BESTn
                     /dev/rmt/c0t0d0BEST    /dev/rmt/c0t0d0BESTnb
                     /dev/rmt/c0t0d0BESTb

Consult the ioscan(1M) manpage for further information about this tool.