Formatting and Allocating a System Volume

If a z/VM® system volume has the wrong format or has not been formatted, your installation can format it for system use. Your support personnel must provide you with the appropriate input.

Before you format and allocate a system volume, you may wish to use the Device Support Facilities program (ICKDSF) to inspect the DASD volume for defective tracks and to assign alternate tracks if required. For more information on using this program, see Running the Device Support Facilities Program, or refer to the Device Support Facilities User's Guide and Reference book.

Note: Although in most instances the CPFMTXA utility can be used for such maintenance procedures, it is recommended that instead, the Device Support Facilities program (ICKDSF) be used in all CP volume maintenance. This is because some DASD devices require the use of the ICKDSF program. In fact, when CPFMTXA is invoked, z/VM will call the ICKDSF program. Only if ICKDSF is available will the system continue with the original command.

Use the CPFMTXA utility or invoke ICKDSF directly to format DASD. For convenience, this section illustrates the use of the CPFMTXA utility. The responses and messages may vary slightly depending on the given scenario.

For more details on the CPFMTXA utility, see the z/VM: CP Commands and Utilities Reference.

To format and allocate a system volume using the CPFMTXA utility:

  1. Vary the device online and attach it to your virtual machine. Enter:
    vary online rdev
    attach rdev to * as vdev
    where:
    rdev
    is the real device number of the DASD.
    vdev
    is the virtual device number you want to assign to the device.
    * (asterisk)
    indicates that you want CP to dedicate the device to your own virtual machine.
  2. Run CPFMTXA. Enter:
    cpfmtxa vdev volid
    where:
    vdev
    is the virtual device number you assigned to the DASD.
    volid
    is the volume identifier you want to assign to the volume that is mounted on this device.
    CPFMTXA tells you that it will erase the cylinders or pages on the disk and asks you if you want to continue. If you answer NO, it does not format the disk. If you answer YES to the continuation prompt, ICKDSF formats the volume.
    Note: If ICKDSF is not on an accessed disk, formatting does not take place.
  3. Enter the input your support personnel supplies.
    For example, if cylinders 0 through 200 are to be used as spooling space, cylinders 201 through 400 as paging space, and the remaining cylinders as temporary disk space, enter:
    spol 0-200
    page 201-400
    tdsk 401-end
    end

    For FBA type DASD page expressions rather than cylinders would be used in the above example.

  4. After the volume is allocated, enter:
    detach rdev from userid
    attach rdev to system as volid
    where:
    rdev
    is the real device number of this DASD.
    userid
    is your user ID.
    volid
    is the volume identifier of the volume that is mounted on this device.

    These commands remove the volume from your virtual machine and attach it to the system.

Note: If you are adding the volume for checkpoint and warm-start data, paging, spooling, dump, directory, or temporary disk space, your installation must have defined the volume identifier of the device by specifying the CP_OWNED statement in the system configuration file. If your installation did not define the volume identifier, CP has no reference to the volume and does not use it for checkpoint and warm-start data, paging, spooling, dump, directory, or temporary disk space.
To find out whether CP is using the volume for these CP functions, enter:
query system rdev
where rdev is the real device number of the DASD you just attached to the system. If CP's response includes the words “ATTACHED CPVOL,” CP is using the volume. If the response includes the words “ATTACHED SYSTEM,” however, CP is not using the volume for the CP functions listed earlier.