It is recommended to use the same I/O configuration (IOCF) on both the source and target SU. If this is not the case, the migrated VM will be displayed with its current state in the VM2000 information commands of the target SU, followed by (DIFF), e.g. RUNNING(DIFF), see "SHOW-VM-ATTRIBUTES (Output attributes of a VM)".
The VM will remain in this state until it is migrated back to its original (source) SU or until the persistent VM on the target SU is reactivated using /DELETE-VM and /ACTIVATE-VM-DEFINITION.
In this state and in the following cases, you will face restrictions on the target SU after the VM Migration:
Device management
If the migrated VM was originally created or activated on the source SU, VM2000 may have to virtualize the subchannel numbers for the VM on the target SU.
A device that was not generated on the source SU cannot be allocated to a migrated VM on the target SU, also see paragraph "BS2000-IPL".
Dynamic configuration modification
A guest system on a migrated VM in
RUNNING(DIFF)state cannot be part of a dynamic configuration modification in the monitor system on the target SU. For this type of guest system, the operator receives theNKR0194message, which has to be answered.If the dynamic configuration modification in the monitor system is executed nevertheless, it will not become active in a guest system of this type and can cause I/O problems in the guest system.Also, in a guest system on a migrated VM that is not in
RUNNING(DIFF)state, some path specific steps of the dynamic configuration modification in the monitor system on the target SU may not be possible to execute. This problem can be solved by starting the guest system on the target SU anew.The dynamic configuration modification is one of the prerequisites of the DPAV function of the IORM utility routine. Accordingly, DPAV cannot be executed for a VM in
RUNNING(DIFF)state.If a VM in
RUNNING(DIFF)state is migrated back to its original (source) SU and the I/O configuration of that SU has changed in the meantime (e.g. because of a dynamic configuration modification), the VM remains in...(DIFF)state on the original (source) SU as well.
BS2000-IPL
In case of a BS2000 IPL, the I/O configuration of the active IOCF of the local (target) SU is used in the guest system. However, the subchannel configuration of the migrated VM under VM2000 corresponds to the I/O configuration of the source SU on which the VM was last created or activated.
This can lead to the following:
Devices of the I/O configuration of the local (target) SU that were not part of the I/O configuration of the original (source) SU, cannot be assigned to the VM in
...(DIFF)state, even after a BS2000 IPL (see paragraph "Device management").When a VM in
...(DIFF)state is migrated back to its original (source) SU, this state is usually deleted. Nevertheless, the devices that were not part of the I/O configuration of the other SU can still not be used in the guest system. They can now be allocated to the VM (no longer in...(DIFF)state) but not attached in the guest system. The guest system does not know the devices after the BS2000 IPL on the other SU. This problem can be solved by starting the guest system anew.