Recommendations for managing logical paths

You do not need to manage logical paths to a control unit if the control unit supports the number of logical paths required by the I/O configuration. However, if a control unit does not support the number of logical paths required by the I/O configuration, you can manage logical paths as follows:
  • Deactivate unneeded logical partitions (LPs).
  • Configure offline unneeded channels. For shared channels, configure offline unneeded channels on an LP basis.
  • For a control unit attached to shared channels, limit the number of LPs that can access the I/O devices attached to the control unit.

    To limit LP access to I/O devices, specify a device candidate list for each I/O device attached to the control unit. The device candidate list (determined by the PART, PARTITION, or NOTPART keyword in the IODEVICE statement) indicates the LPs that can access the I/O device. LPs not in the device candidate list cannot access the I/O device.

    A shared channel does not establish a logical path from an LP to an attached control unit if all the I/O devices attached to the control unit deny access to the LP.

  • Use the director to block ports or prohibit dynamic connections or communication between ports.
  • Combinations of the preceding.