What you should know about the z/VM *MONITOR record reader device driver

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7.1 z/VM guest

The data that is collected by *MONITOR depends on the setup of the monitor stream service.

The z/VM® *MONITOR record reader device driver only reads data from the monitor DCSS; it does not control the system service.

z/VM supports only one monitor DCSS. All monitoring software that requires monitor records from z/VM uses the same DCSS to read *MONITOR data. Usually, a DCSS called MONDCSS is already defined and used by existing monitoring software.

If a monitor DCSS is already defined, you must use it. To find out whether a monitor DCSS exists, issue the following CP command from a z/VM guest virtual machine with privilege class E:
q monitor
The command output also shows the name of the DCSS.
Using kdump: If you use kdump, ensure that the monitor DCSS does not overlap with the storage area 0 - <crashkernel size>. If the DCSS is already defined and overlaps with the crashkernel storage area, it must be removed and defined again at a suitable location.

Further information

  • See z/VM: Saved Segments Planning and Administration, SC24-6322 for general information about DCSSs.
  • See z/VM: Performance, SC24-6301 for information about creating a monitor DCSS.
  • See z/VM: CP Commands and Utilities Reference, SC24-6268 for information about the CP commands that are used in the context of DCSSs and for controlling the z/VM monitor system service.
  • For the layout of the monitor records, go to www.ibm.com/vm/pubs/ctlblk.html and click the link to the monitor record format for your z/VM version.