Notes on configuration for VM2000 operation

In theory the peripheral devices belonging to a Server Unit can be freely distributed over the virtual machines. The following guidelines should be borne in mind when configuring the virtual machines:

Notes on configuration for all Server Units

• The operation of the guest system on a VM (operating) is normally carried out by means of BS2000 consoles (see "Operating the guest systems using BS2000 consoles").

  Alternatively guest systems can also be operated via $VMCONS.

Notes on configuration for the SU x86

• In each guest system (and the monitor system as well), the configuration states of the KVP devices that are not used as a KVP console in the relevant guest system should be set to DETACHED via the startup parameter service (IOCONF parameter set, MODIFY-IO-UNIT statement). The KVP devices used in the guest system should remain ATTACHED (default).

Notes on configuration for the SU /390

• If all KVP devices for guest systems have been generated as DETACHED (recommended) during hardware generation, and there are also no redundant KVP devices (KVP devices of the redundant MU that are assigned to a VM but are not being used as an IPL console), the configuration states of the redundant KVP devices in every guest system should be set to ATTACHED in the startup parameter service (IOCONF parameter service, MODIFY-IO-UNIT statement).

• If different virtual machines are working with channel devices that are attached to one device controller, a very heavy I/O utilization of these devices may result in bottlenecks. To avoid this, all the devices attached to the same device controller should be assigned to one virtual machine wherever possible.

• In VM2000 operation, disk devices can be assigned to the VMs for shared use. If a disk device is shared by at least two VMs on an SU /390, all of the input/output traffic of the shared disk devices is coordinated by the VM2000 hypervisor. On SU /390, disk devices should therefore not be operated as shareable unnecessarily.