Tip: zEC12 delivered significant enhancements to the D CF command. This section shows the command on a CPC prior to zEC12 and also on a zEC12. It is important to note that the CF does not have to be running on a zEC12 or zBC12. If z/OS is running on a zEC12 or later, detailed information will be provided about the z/OS end of the link. If the CF is running on a zEC12 or later, detailed information about that CF’s end of any CF-to-CF links will be provided.

Tip: More information about each CHPID is provided by RMF, both in Monitor III and in a new Channel Path Details RMF Post Processor report. For more information about the enhanced RMF support, refer to Appendix A, “Resource Measurement Facility” on page 233.

Important: If you review the output from the command, you will see that it reports the CHPIDs that are defined to connect to the CF. However, it does not provide any information about the relationship between those CHPIDs and the underlying InfiniBand infrastructure. At the time of writing, it is not possible to get this information from z/OS; it is only available on the SE or in hardware configuration definition (HCD). Therefore, although the D CF command is effective for checking that the CF is online and how many CHPIDs are online, it does not help identify any single points of failure that might exist in the underlying coupling links.

Note: Just as the D CF command provides additional information when issued on a zEC12 or later, similarly the D M=CHP command also provides additional information, so we will show the result of a D M=CHP command separately for zEC12 and for pre-zEC12.

Tip: Before changing any aspect of the system configuration, it is always useful to display the status before making any changes. This information can be invaluable if you later encounter problems trying to bring the configuration back to its original status.

Note: Because CHPIDs can be shared by multiple LPARs, configuring a shared CHPID offline in one LPAR will not make the CHPID go physically offline. When the CHPID is taken offline in the last LPAR that is using that CHPID, it will go physically offline at that point. With traditional coupling links, there was a one-to-one relationship between CHPIDs and links, so after the CHPID was configured offline in all LPARs using that CHPID, the link could be opened at that point. However, with InfiniBand links, many CHPIDs could be associated with a single link. The link should not be opened until all the CHPIDs associated with both ends of that link have been configured offline in all LPARs using each of those CHPIDs. The physical status of the CHPIDs sharing a link can be checked on the HMC or the SE, as discussed in 7.4.4, “Displaying the status of a CIB link (CPC view)” on page 219.

Important: Use care when making dynamic changes that affect the number of CHPIDs assigned to a HCA3-O 12X port. Always ensure that there is at least one other, active, link connecting to the same CFs and the same processor as the port you are changing. Also, remember that with InfiniBand links, multiple sysplexes can be using a single link, meaning that a change that causes a port to reinitialize can potentially impact multiple sysplexes. This is a significant change from traditional coupling links, where each link can only be used by one sysplex.

Note: All coupling CHPIDs are shown as type CFP regardless of the actual physical link type.

Important: Remember that the CF0075I Last link message applies to peer CFs, as well as to connected z/OS LPARs. If fewer links are used to connect the CFs to each other than are used to connect the CF to z/OS, it is possible that you will receive this message even though there are still more CHPIDs available to communicate with z/OS. The message does not indicate which LPARs the CF is going to lose communication with.

Note: If structures are present in the CF, the shutdown operation is canceled and the CF continues operating. This is a safer way to shut down a CF than using the Deactivate task on the HMC. Even though the operator is warned that doing a Deactivate could be disruptive, the same message is issued regardless of whether the CF contains structures or not. If the operator replies to proceed with the deactivation, the CF will be deactivated, regardless of whether it contains structures or not. If the SHUTDOWN completed successfully for the CF, there will be no need to then perform a DEACTIVATE for the CF. In the case where a SHUTDOWN cannot be completed successfully (for the last CF in the sysplex, for example), the HMC DEACTIVATE function must be used.

Important: The information in this section is relevant to both z196 and zEC12 CPCs. However, on zEC12 and later, you can use the D CF command to obtain information that was previously only available on the HMC or SE. If your system is running on a zEC12 or later, check if the D CF command will provide the information you require before using the SE.

Note: Channels can be displayed on the SE by selecting the processor or an image. The key difference is that the PCHID or physical link status is shown when selecting the processor perspective, whereas the logical channel or link status is shown if you select the image perspective.

Note: All fanouts have an AID assigned but only PSIFB fanouts use them. The MBA and HCA-IO fanouts do not use an AID.

Important: When performing a toggle action, you must select the LPAR where you want the change to take effect. For example, if LPARs A21 and A22 are using CHPID 93 in CSS 2, and you attempt to perform the toggle action after selecting both LPARs, you will be presented with a panel indicating that the action can only be performed against one LPAR, and asking you to select which of the two LPARs you want to perform the action against.

Note: If you have a valid reason for toggling the CHPID offline to several LPARs simultaneously, you can do that from the SE. Select the CHPIDs that you want to toggle from the channel list and select the Configure On/Off option under Channel Operations. If the CHPID is in use by multiple LPARs, you will be asked to select which LPARs you want to be affected by the toggle action.

Tip: On a zEC12 or later, much of the information that you can obtain about a CIB CHPID from the SE can also be obtained using the z/OS D CF or D M=CHP(xx) command.

Note: A PCHID in the range from 0700 to 07FF lacks the exact one-to-one relationship between the identifier and the physical location. For more information see 2.4.2, “VCHID - Virtual Channel Identifier” on page 28.

Tip: All parts of the window and the table can be readjusted in size to provide more flexibility in viewing specific information.

Tip: You can go directly to Channel Problem Determination from here. This option is described in 7.4.7, “Useful information from the Channel Problem Determination display” on page 224.

Tip: On a zEC12 or later, much of the information that you can obtain about a CIB CHPID from the SE can also be obtained using the z/OS D CF or D M=CHP(xx) command.

Note: A PCHID in the range from 0700 to 07FF lacks the exact one-to-one relationship between the identifier and the physical location. For more information see 2.4.2, “VCHID - Virtual Channel Identifier” on page 28.

Important: When looking at a shared coupling link from two logical partitions (Image view), the coupling link (CHPID) might have a different status for each. It is essential to select the CHPID through the desired logical partition from which you want to view.

Note: In the panel, the Link speed field actually reports the speed of each fibre pair in the link (for example, it could be 2.5 Gbps for a Single Data Rate link or 5.0 Gbps for a Double Data Rate link). To determine the full bandwidth of the link, multiply the value in the Link speed field by the number of lanes, as reported in the Link width field. Thus, in this example, the design bandwidth of the link is 6 GBps (5.0 Gbps per lane times 12 lanes).

Note: The CPATH and the CSYSTEM must match the Tag value from the attached node.

CSS/Tag

1

2

3

4

5

6

7

8

9

A

B

C

D

E

F

0

X

X

X

X

X

X

X

X

1

X

X

X

X

X

X

X

X

2

X

X

X

X

X

X

X

X

3

X

X

X

X

X

X

X

X

Note: At the time of writing, this panel is the only place where you can obtain information about the physical type (HCA1, HCA2, or HCA3, and 1X or 12X) and protocol (IFB or IFB3).

Note: If the z/OS LPAR is not activated, the channel status of “Online/Loss of Signal” or “Online / Sequence Timeout” is a normal status.

Note: If the CHPID is only online on the z/OS LPAR, then configure it off first using the procedure from the HMC, as described in 7.4.3, “Toggling a CHPID on or offline using HMC” on page 216.

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