Switch Operations Facility › SOF Server Configuration and Start-up › Define Switches

Define Switches

Normally, the SOF server automatically discovers all switches in the I/O configuration. There may be situations where the SOF server is not able to identify a switch, or may identify a switch improperly. Those situations results in SOF being unable to properly correlate the switch among the multiple z/OS systems.

The situations that follow require adding a DEFINE SWITCH command in the INITCMDS file:

• Identify the switch to the local SOF server

  On a DEFINE SWITCH command, specify the logical device number of the switch as specified in the IODF of the local system. This specification identifies the switch to the local SOF server. If this number is different on different systems in the SOF complex, then a different DEFINE SWITCH command must be directed to each different system. This procedure can be done by using the IFSYS statements in a shared INITCMDS file, or by using a different INITCMDS file for each different system.

• Specify a DEVID for the switch that SOF uses to correlate the switch among the multiple z/OS systems

  On each DEFINE SWITCH command that is issued for the same switch, specify the same arbitrary DEVID. This procedure lets SOF know which local switches to correlate globally as the same switch on multiple z/OS systems in the SOF complex. DEVIDs are further discussed in subsection Hardware Device IDs in section SOF Command Interface.

The DEFINE SWITCH command syntax is described in Miscellaneous Commands.

Use DEFINE SWITCH command in the following situations:

• A switch is not defined to a z/OS system in the SOF complex. That is, the switch has no device number and no UCB as an I/O device.
• A switch is sometimes OFFLINE to a z/OS system in the SOF complex.
• The I/O device number does not match the logical switch number. For this case, the LSN keyword must be used to identify an internal identity of the switch.
• A single physical switch is partitioned as multiple logical switches. Each logical switch presents the same serial number to a z/OS system in the SOF complex.

For any switch, as long as there is a UCB for the switch on at least one z/OS system in the SOF complex and the switch is online to that system, all SOF connectivity control commands that are directed to the switch functions normally.

Example: Switch between Systems

A two-system SOF complex, follows with definitions:

• A switch is defined as logical device number 0001 in the IODF for SYSTEMA.
• This same switch is defined as logical switch number 0002 in the IODF for SYSTEMB.

The following commands in a shared INITCMDS file would enable SOF to correlate the switch between systems:

IFSYS SYSTEMA
  DEFINE SWITCH 0001 009032.005.IBM.02.FAKESERIAL03.0000
ENDSYS
IFSYS SYSTEMB
  DEFINE SWITCH 0002 009032.005.IBM.02.FAKESERIAL03.0000
ENDSYS

Important! After starting SOF for the first time, we recommend that you verify the switches as discovered by SOF in the shared I/O configuration. Use the SOF display commands or OPSVIEW option 3.5, to determine if DEFINE SWITCH commands are required at your site.