How to Change Your Configuration

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How to add a PAGING DASD to a z/VM system.

  1. Ensure that you have a RESERVED slot on a CP_Owned DASD, enter:
       CP Query CPOWNed
    If none of those displayed bear the Status: Reserved
    then you cannot add a PAGE volume dynamically. The best you can do is update "SYSTEM CONFIG" on MAINT's CF1 (and perhaps CF2, CF3) disk to include additional "Reserved" slots.

    To ensure that you have slots available to use with the DEFINE CPOWNED command, place a:
       CP_Owned Slot 255 RESERVED
    statement at the end of your CP_Owned statements in SYSTEM CONFIG. This will define all 255 slots (unless otherwise specified) as RESERVED. That is probably a **GOOD THING** thing for every z/VM sysprog do right now, before an urgent need!

    If you did not have any spare RESERVED SLOTs, you may continue with these steps, but the new page volume will not come online until the next z/VM system IPL.

  2. Find an available DASD volume real device (rdev) address accessible to your z/VM system.

  3. Decide on an unused DASD label (volid, or: volser) for the soon-to-be paging volume.

  4. Run CPFMTXA against that DASD, formatting the whole DASD (0 - END), assigning the label as decided above, and allocating:
      - Cylinder 0 (zero) as PERM, and
      - Cylinders 1-END as PAGE
    In a production environment, there are major performance benefits to allocating whole DASD to PAGE and SPOOL areas -- *not* sharing them with other allocation usage.
    Strictly speaking, defining cyl 0 as perm is unnecessary for modern releases of z/VM. But one cylinder of "unused" space is cheap when compared to accidentally formatting that volume's Cylinder 0, thus wiping out the existing Allocation Bitmap - especially if you do not have documentation on what it had been! Call it a "Best Practice". with doing this.

  5. Update the "SYSTEM CONFIG" file on MAINT's CF1 disk using whatever procedures you already use. E.g. - Find a free CP_OWNed 'SLOT', change that to match the new page DASD volser, and mark that as CP-"OWN"ed. E.g. if "volser" is "VMPG01" and slot 11 is not already assigned:
       CP_Owned Slot 11 VMPG01 OWN
    That changed "SYSTEM CONFIG" file will be effective at the next z/VM system IPL.

  6. File "SYSTEM CONFIG", and run CPSYNTAX against the updated "SYSTEM CONFIG" file to check for errors. The CPSYNTAX MODULE resides on MAINT's 193 disk. If there are errors, correct them and re-run CPSYNTAX.

  7. From the userid that formatted/allocated the new paging DASD, enter:
       CP DETach rdev

  8. Notify CP that the CPOWNED SLOT has been changed from RESERVED to OWN using the CP DEFINE CPOWNed command. Following the example above, it would be entered as:
       CP DEFine CPOWNed Slot 11 VMPG01 Own

  9. Absent any errors, bring the volume online to CP by entering:
       CP ATTach rdev SYSTEM
    There is no need for 'CP START DASD rdev PAGE'. CP START DASD is nothing more than undrain. If you haven't done DRAIN, don't bother with START.

2010-06-17 Version 1.5a