I/O Device Candidate List; Procedure For Defining Shared Channel Paths; Communicating By Means Of Escon Or Ficon Ctc - IBM Z9 Planning Manual

I/O Device Candidate List

The I/O device candidate list specifies the LPs which can access the device. You
can use the I/O device candidate list to restrict LP access to I/O devices on shared
channel paths. If you do not specify an I/O device candidate list, all LPs that share
the channel paths, to which the device is attached, can have access to the device.
For coupling facility devices, the device candidate list is not supported.

Procedure for Defining Shared Channel Paths

To share channel paths, use the following general procedure:
1. Select which I/O devices to access through shared channel paths
2. Select the LPs that will share channel paths
v Specify the desired channel paths as shared
v Use the access list and candidate list of the desired shared channel path to
select which LPs can access that shared channel path.
3. For each I/O device that will be on a shared channel path, you can use the I/O
device's candidate list to restrict which LPs can access that I/O device.
4. Make physical connections to the shared channel paths and the I/O devices.
5. Update the software I/O configuration for the control programs running in LPs
that can access devices through shared channels.
6. Use IOCP or HCD to create an IOCDS that defines the I/O configuration,
including shared channel paths, to the CPC channel subsystem. The channel
subsystem includes all channel paths, control units, and I/O devices accessible
by all LPs.

Communicating by Means of ESCON or FICON CTC

You can connect shared or unshared CNC or FCV channel paths to shared or
unshared CTC channel paths for the purpose of CTC communication. The
connected CNC or FCV and CTC channel paths can be on the same CPC (to
communicate between the LPs on that CPC) or on different CPCs.
You can connect shared or unshared FC channel paths to shared or unshared FC
channel paths for the purpose of CTC communication. The connected FC channel
paths can be on the same CPC (to communicate between the LPs on that CPC) or
on different CPCs.
CTC communications involving a shared channel path require the specification of
control unit logical addresses. The control unit logical address identifies the MIF
image ID number for the LP to which the channel path is to communicate. If the
remote channel path is not shared, the logical address must be zero or not
specified. If the remote channel path is shared, the logical address must equal the
desired MIF image ID number for the LP that the shared channel path can access.
If the remote channel path is a shared FC channel path and the target LP has a
CSS ID other than zero, then the logical address must equal the combination of the
desired CSS ID and the MIF image ID for the LP with which you want to
communicate. For example, if the remote channel path is shared within CSS 1 and
you want to communicate with the LP that has MIF image ID 5, specify logical
address 15. You must define a control unit and a control unit logical address for
every LP that you want to communicate with.
For additional information, see zSeries ESCON or FICON Channel-to-Channel
Reference, SB10-7034.
Chapter 3. Determining the Characteristics of Logical Partitions
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