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man pages section 4: Device and Network Interfaces

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Updated: Wednesday, July 27, 2022



devchassis - device name file system


The chassis subdirectory of the /dev devfs(4FS) file system provides a location-oriented name space. The /dev/chassis name space is maintained by the devchassisd(8) smf service. The /dev/chassis name space is structured by chassis, receptacle, and current occupant. Within the chassis/receptacle name space, the current occupant is maintained as a dynamic symlink into the /devices file system.

     [/<occupant-type> -> /devices/...]]

An empty receptacle is represented as an empty directory.

If an fmadm(8)—managed <alias-id> exists, then the <chassis-name>.<chassis-serial> is replaced by a managed <alias-id>. A managed <alias-id> can establish the physical location of chassis, like a building, lab, rack, and chassis U-number range inside the rack.

There is always one well-known <alias-id> associated with internal locations: SYS. This <alias-id> cannot be modified.

A <receptacle-name> is associated with chassis silk-screen labeling of receptacles (like disk bays). Multiple <receptacle-name> directories can be used before coming to an occupant symlink.

The /dev/chassis name space allows you to administer the machine based on physical location.

# format /dev/chassis/SYS/HD0/disk

# zpool create tank mirror \
        /dev/chassis/RACK29.U01-04/DISK_00/disk \

fmd(8) machine topology understanding is required to drive the creation and maintenance of the /dev/chassis name space. If this understanding is lacking, the /dev/chassis name space will be lacking. fmd(8) and devchassisd(8) operation is coordinated using the contents of /etc/dev/cro_db. This same data file is also used by the croinfo(8) utility.



Directory under the /dev file system mount point that provides, when possible, a location-oriented device name space.


Data file created by fmd(8) used to obtain information about chassis, receptacles, and occupants.

See Also

devfs(4FS), devices(5), croinfo(8), devchassisd(8), fmadm(8), fmd(8)


To prevent stale links, the entire /dev/chassis name space is removed during each boot and reestablished when both fmd(8) and devchassisd(8) are running. If devchassisd(8) is not running, the /dev/chassis name space does not exist.

Gaps in fmd(8) topology representation result in gaps in the /dev/chassis name space.