Examples of udev-created SCSI device nodes

Device nodes that are based on device names

udev creates device nodes that match the device names that are used by the kernel. These standard device nodes have the form /dev/<name>.

The examples in this section use standard device nodes as assigned by the SCSI stack. These nodes have the form /dev/sd<x> for entire disks and /dev/sd<x><n> for partitions. In these node names <x> represents one or more letters and <n> is an integer. See Documentation/devices.txt in the Linux® source tree for more information about the SCSI device naming scheme.

To help you identify a particular device, udev creates additional device nodes that are based on the device's bus ID, the device label, and information about the file system on the device. The file system information can be a universally unique identifier (UUID) and, if available, the file system label.

Device nodes that are based on bus IDs

udev creates device nodes of the form

/dev/disk/by-path/ccw-<device_bus_id>-fc-<wwpn>-lun-<lun>

for whole SCSI device and

/dev/disk/by-path/ccw-<device_bus_id>-fc-<wwpn>-lun-<lun>-part<n>

for the <n>th partition, where <wwpn> is the worldwide port number of the target port and <lun> is the logical unit number that represents the target SCSI device.

Note: The format of these udev-created device nodes has changed and now matches the common code format. Device nodes of the prior form, ccw-<device_bus_id>-zfcp-<wwpn>:<lun> or ccw-<device_bus_id>-zfcp-<wwpn>:<lun>-part<n>, are no longer created.

Device nodes that are based on file system information

udev creates device nodes of the form

/dev/disk/by-uuid/<uuid>

where <uuid> is a unique file-system identifier (UUID) for the file system in a partition.

If a file system label is assigned, udev also creates a node of the form:

/dev/disk/by-label/<label>

There are no device nodes for the whole SCSI device that are based on file system information.

Additional device nodes

/dev/disk/by-id contains additional device nodes for the SCSI device and partitions that are all based on a unique SCSI identifier that is generated by querying the device.