Accessing Devices

You need to know how to specify device names when using commands to manage disks, file systems, and other devices. In most cases, you can use logical device names to represent devices that are connected to the system. Both logical and physical device names are represented on the system by logical and physical device files.

How Device Information Is Created

When a system is booted for the first time, a device hierarchy is created to represent all the devices connected to the system. The kernel uses the device hierarchy information to associate drivers with their appropriate devices, and provides a set of pointers to the drivers that perform specific operations. For more information on device hierarchy, see OpenBoot 3.x Command Reference Manual.

How Devices Are Managed

The devfsadm command manages the special device files in the /dev and /devices directories. By default, the devfsadm command attempts to load every driver in the system and attach to all possible device instances. Then, devfsadm creates the device files in the /devices directory and the logical links in the /dev directory. In addition to managing the /dev and /devices directories, the devfsadm command also maintains the path_to_inst(4) instance database.

Both reconfiguration boot processing and updating the /dev and /devices directories in response to dynamic reconfiguration events is handled by devfsadmd, the daemon version of the devfsadm command. This daemon is started from the /etc/rc* scripts when a system is booted.

Since the devfsadmd daemon automatically detects device configuration changes generated by any reconfiguration event, there is no need to run this command interactively.

For more information, see devfsadm(1M).

Device Naming Conventions

Devices are referenced in three ways in the Solaris environment.

• Physical device name – Represents the full device pathname in the device information hierarchy. Physical device names are displayed by using the following commands:

  • dmesg

  • format

  • sysdef

  • prtconf

  Physical device files are found in the /devices directory.

• Instance name – Represents the kernel's abbreviation name for every possible device on the system. For example, sd0 and sd1 represent the instance names of two disk devices. Instance names are mapped in the /etc/path_to_inst file and are displayed by using the following commands:

  • dmesg

  • sysdef

  • prtconf

• Logical device name – Used with most file system commands to refer to devices. For a list of file commands that use logical device names, see Table 30–1. Logical device files in the /dev directory are symbolically linked to physical device files in the /devices directory.