Changing channel paths

To change channel path data you have to follow the same panel flow as for defining channel path data:

• Changing channel path characteristics
• Changing channel path access and candidate list

The following steps describe the panel flow and where you can change the data.

1. On the Channel Path List, select a channel path and the Change action from the context menu (or action code  c ).
2. On the following Change Channel Path Definition panel you can change channel path definitions such as:
   • Channel path ID (see also Changing processors for an example of the Update Channel Path Identifiers panel, and how to change the CHPID values)
   • Channel path type (see Changing the type of a channel path)
   • Operation mode (see Changing the operation mode of a channel path)
   • PCHID
   • Description
   • If connected to a switch
     • Dynamic switch ID
     • Entry switch ID
     • Entry port
3. After pressing the Enter key, the Define Access List is displayed. Select one or more partitions to be included in the access list.
4. After pressing the Enter key again, the Define Candidate List is displayed (if applicable). Select one or more partitions to be included in the candidate list.

You can also change channel path definitions (except the channel path ID) and the channel path’s access and candidate list by simply typing over the appropriate values on the Channel Path List. To change the access and candidate list definitions, scroll to the right to see the channel path/partition matrix (refer to Figure 50). Overwrite the values in the channel path/partition matrix with either a for access list and c for candidate list.

Changing the ID of a channel path

Changing the ID of a channel path may first require the disconnection of the entry switch and entry port on the channel path. If channel paths of multiple processors or channel subsystems (e.g. spanned CHPIDs) connect to the same entry switch and entry port, proceed as follows:

1. Remove the entry switch and entry port from the channel path definitions.
2. Change the channel path ID of the corresponding channel paths.
3. Once again add the entry switch and entry port to the channel paths.

Changing the type of a channel path

Changing the type of a channel path from parallel to serial (or vice versa) will result in changing the type of all other channel paths that are attached to the affected logical control units. When changing the type of a channel path:

• The new/changed channel path type must not conflict with the already existing channel path IDs, control unit and device parameters. Adjust the values of the affected control units and devices according to the rules of parallel or serial channel path type. (For information on how to change control unit processor attachment and device parameters, see: Changing control units.)
• When changing from serial to parallel, you have to disconnect the entry switch and entry port first, if the channel path is connected to a switch.
• When changing a channel path of type BL or BY that is connected to more than one control unit, the channel path has to be defined to a corresponding CVC (converter channel path) first and then be changed to serial.

Changing the type of a coupling facility channel path

To change the type of CF channel paths, disconnect the channel path you want to change before performing the type change. Any coupling facility devices associated with the changed channel path are removed by HCD. The associated control unit is removed only when the last connection to the coupling facility to which the control unit belongs is broken. (For details on that task, see Establishing coupling facility channel path connections.)

Changing the operation mode of a channel path

Changing the operation mode of a channel path is dependent on its type. For example, BL, BY, CVC, CBY, and CF receiver channel paths cannot be shared.

Before you can change the operation mode of a channel path, the rules for partition access and candidate lists of those channel paths that are attached to the affected logical control units must conform to the rules for the new operation mode. You have to check which partitions have access to these channel paths. When changing the channel path operation mode from SHR to REC or DED, you first have to remove partitions in the appropriate access and candidate lists. The partition lists for the affected logical control units have to be changed when the mode change has been done.

Changing the operation mode of a channel path to SPAN

If you want to change the operation mode to SPAN for applicable channel path types, you must ensure that the CHPID is unused in those channel subsystems into which it should be spanned. This means that the CHPID whose operation mode you want to change, must be unique throughout the processor complex. So you need to distinguish the following scenarios:

• For an existing shared CHPID that is uniquely defined throughout all LCSSs of the processor:

  Enlarge its access and candidate lists with partitions from other channel subsystems. For a shared CHPID, in the Channel Path List, scroll right once for each CSS of the current processor to see the available partitions that you can specify for access or candidates.

     Goto  Filter  Backup  Query  Help
   ------------------------------------------------------------------------------
                                 Channel Path List       Row 1 of 1 More: <     >
   Command ===> _______________________________________________ Scroll ===> CSR
  
   Select one or more channel paths, then press Enter. To add, use F11.
  
   Processor ID : XMPP01     CSS ID  : 0   LPAR01 - LPAR02
   1=OS LPAR01    2=OS LPAR02    3=             4=             5=
   6=             7=             8=             9=             A=
   B=             C=             D=             E=             F=
           PCHID                   I/O Cluster  --------- Partitions 0x ----- 
   / CHPID AID/P Type+ Mode+ Mng   Name +       1 2 3 4 5 6 7 8 9 A B C D E F
   _ 00    ___   IQD   SPAN  No    ________     a c  _ _ _ _ _ _ _ _ _ _ _ _ _
   ******************************* Bottom of data ********************************

   1=OS LPAR01 2=OS LPAR02  and  --------- Partitions 0x -----  in our example indicate that partitions  LPAR01  and  LPAR02  are available as partitions of usage type OS in the CSS with ID=0 (0x).

  With the codes  a  and/or  c  you specify which partitions you want to access. Note that if the CHPID's operation mode in column Mode of the Channel Path List was SHR before your changes, it is set to SPAN automatically after specifying partitions from different channel subsystems (0x, 1x, ...).

• For an existing dedicated or reconfigurable CHPID that is uniquely defined throughout all LCSSs of the processor:

  You can change its operation mode to SPAN using the Change action from the context menu (or action code  c ) on the Channel Path List. In the subsequent Define Access List and Define Candidate List, you must select at least two partitions from different channel subsystems, because otherwise, HCD sets the operation mode to SHR.

• For any existing CHPID that is multiply defined throughout the LCSSs in the processor complex:

  You must delete the CHPID from all but one LCSS, before you can change its operation mode to SPAN, using the Change action from the context menu (or action code  c ) on the Channel Path List and selecting appropriate partitions from the Define Access List and the Define Candidate List.

When spanning a channel path, that has control unit(s) (and devices) attached, to a new CSS, HCD invokes a dialog asking whether these control unit(s) (and devices) should also be reachable from the new CSS.

*---------- Confirm Copy Control Unit and Device Attachments -----------*
|                                                                       |
|                                                                       |
| Control unit and device attachments are defined on the named channel  |
| path, which are eligible to be copied to all channel subsystems the   |
| channel path gets newly spanned to. To confirm copy action, select    |
| Yes. To not copy any control unit or device attachment, select No.    |
|                                                                       |
| Processor ID . . . . . : ERV01      mix system                        |
| Channel subsystem ID . : 0          zos prod 1 / spare                |
| Channel path ID  . . . : 11                                           |
|                                                                       |
| Copy confirmed . . . . . 1   1.  Yes                                  |
|                              2.  No                                   |
|                                                                       |
|  F1=Help    F2=Split   F3=Exit    F9=Swap   F12=Cancel                |
*-----------------------------------------------------------------------*

Specify Yes, if you want all existing CU and device connections of the designated channel path to be copied to all channel subsystems the channel path gets newly spanned to.

Changing the operation mode of CF channel paths

CF channel paths that connect a processor to the same coupling facility partition via the same control unit must be either all shared or all nonshared. Hence, if you want to change the operation mode for one channel path (from non-SHR to SHR), you have to change it for all. To do this proceed as follows:

1. Disconnect all receiving CF channel paths that connect a processor to the same coupling facility partition (see Disconnecting coupling facility channel path connections).
2. Change the operation mode of all sending CF channel paths.
3. Re-establish the connections for all channel paths that you disconnected in step 1.

The associated coupling facility control unit and coupling facility devices are removed and generated again by HCD.

Changing a coupling facility connection

To change a coupling facility connection:

1. Disconnect a connection (see Disconnecting coupling facility channel path connections).
2. Establish the new connection (see Establishing coupling facility channel path connections).

It is not possible to include the first CF or CF/OS LP in, or remove the last CF or CF/OS LP from, the combined access and candidate list of a connected CF peer channel. Instead, the CF connection first has to be removed. Then, the CF LP can be connected to or disconnected from the CF peer channel path; afterwards, the CF peer connection can be reestablished. This is to avoid implicit generations of deletions of CF control units and devices.