Persistent device configuration

Use the chzdev command to persistently configure your devices and device drivers and the lszdev command to view your configuration.

Mainframe-specific devices, such as DASDs, FCP devices, and network devices require special configuration steps before they can be used. Tools are available that configure devices, for example chccwdev and znetconf, but this type of configuration is not preserved across reboots.

The chzdev command facilitates persistent configuration. The command performs all configuration steps that are required to make devices operational, for example, as a block device, a character device, or a network interface.

The following device types are supported:

FICON-attached direct access storage devices (DASDs)
SCSI-over-Fibre Channel (FCP) devices and SCSI devices
OSA-Express and HiperSockets network devices
LAN-Channel-Station (LCS) network devices
Channel command word (CCW) devices that are not covered by any other device type, for example the 3215 console, 3270 terminal devices, z/VM reader and puncher devices, and CCW tape devices.

The chzdev and lszdev commands are included in the s390-tools package. chzdev configures the devices and device drivers in two ways:

In the currently running configuration, called the active configuration
In configuration files such as udev rules, called the persistent configuration

The lszdev command displays configuration information about devices and device drivers. For details, see lszdev - Display z Systems device configurations.

For details about the chzdev command, see chzdev - Configure z Systems devices.

Note: Distributions might use tools that are not aligned with lszdev and chzdev. Using such distribution tools alternating with chzdev can result in conflicting configuration settings.

Device ID

The chzdev and lszdev commands use device IDs to identify devices. For CCW devices and CCW group devices, this device ID is the device bus-ID.

The device bus-ID is of the format 0.<subchannel_set_ID>.<devno>, for example, 0.0.8000.

Tip: For device bus-IDs with a leading "0.0", you can shorten the specification to just the device number (devno). For example, you can shorten 0.0.0b10 to 0b10.

Other device categories can have different IDs. For example, SCSI devices have a triplet device ID consisting of a device number, a WWPN, and a LUN.

Configuring device drivers

You can use the chzdev command to modify device driver attributes, for example module parameters such as DASD's eer_pages. You select a device driver, rather than a device, by using the --type option. Device drivers can be selected by type or sub-type, for example DASDs are of type dasd, but have the sub-types dasd-fba and dasd-eckd.

chzdev syntax overview


>>-chzdev--| Device or device type selection |--| Actions |----->

>--| Options |-------------------------------------------------><

Where the different command sections have these meanings:

Device or device type selection

Select devices by device ID, device state, or function. Select device types by specifying a device type and the --type option. For details about selecting devices or device types, see Selecting devices and device drivers.

Actions

Perform an action against the selected devices. For details about these actions, see:

Options: Choose how to apply the command, for example as a test run, as applying to the persistent configuration only, or as running in quiet mode. Options include --dry-run, --verbose, --quiet, and --yes. For the complete list of options, see chzdev - Configure z Systems devices

lszdev syntax overview


>>-lszdev--| Device or device type selection |--| Options |----><

Where the different command sections have these meanings:

Device or device type selection: Select devices to display by device ID, device state, or function. For details about selecting devices, see Selecting devices and device drivers. If no selection is made, all existing and configured devices are displayed.

Options

Choose the configuration information, and how to display it.

To display a list with information about all devices, specify only lszdev without options. You can restrict output to a single device, a device type, or a range of devices. You can control what information is included by specifying output columns.
To display details about a single device, specify the device and the --info option.