Restarting a logical link

If a restart is pending on a logical link because of a physical link failure, reestablish communications between both systems through an alternative physical link.

Restriction: In a TCP/IP generic resource group, where a physical link is defined in multiple IMS systems, if a logical link is in a PSTOPPED ERE state on any IMS system in the group, do not start a logical link that uses the same physical link on any other IMS system in the group. Before you can start a logical link on the same physical link on another system, you must clear the affinity of the ERE link either by shutting it down normally or by resetting it to a COLD state.

As a precaution, display the affinity status of an MSC link on its current IMS system before moving the link by restarting it on another IMS system. If the affinity is still active, shutdown the link normally, which resets the affinity status. If the link cannot be shut down normally, set the link to COLD status by issuing either the type-1 command /CHANGE LINK linknum FORCSESS | SYNCSESS COLDSESS or the type-2 command UPDATE MSLINKNAME(linkname) SET(SYNCOPT(COLDSESS)

Attention: Changing the link status from ERE to COLD or moving a link in ERE status and restarting it on another IMS system prevents the synchronization of the message sequence numbers during restart, which can cause the duplication or loss of messages.

Procedure

  1. If the link uses TCP/IP or VTAM®, before you assign a logical link either to or from an MSPLINK name, stop the physical link by issuing one of the following commands:
    • The type-1 command /PSTOP MSPLINK
    • The type-2 command UPDATE MSPLINK NAME(msplinkname) STOP(LOGON)
    • For links in a TCP/IP generic resource group only, the type-2 command UPDATE MSPLINK NAME(msplinkname) STOP(GENLOGON)
  2. Reassign the logical link to the alternate physical link by using either of the following commands:
    • The type-1 command /MSASSIGN
    • The type-2 command UPDATE MSLINK NAME(linkname) SET(MSPLINK(msplinkname))
  3. If the link uses TCP/IP or VTAM, restart the physical link by issuing one of the following commands:
    • The type-1 command /RSTART MSPLINK
    • The type-2 command UPDATE MSPLINK NAME(msplinkname) START(LOGON)
    • For links in a TCP/IP generic resource group only, the type-2 command UPDATE MSPLINK NAME(msplinkname) START(GENLOGON)
  4. Start the logical link by issuing one of the following commands:
    • The type-1 command /RSTART LINK
    • The type-2 command UPDATE MSLINK NAME(linkname) START(COMM)