Using the master configuration file (MCF)

The master configuration file (MCF) is an HCM configuration stored on the host as a central shared repository. The MCF concept is introduced in Introduction to the master configuration file concept and brings along the following main advantages:

• Several HCM users can work cooperatively and safely on a single configuration, sequentially sharing the configuration in connected mode.
• There is no longer the need to keep this critical data on workstations, maybe even distributed as multiple local copies across your installation, but you can maintain a single consistent data set on the mainframe.

Sharing an HCM configuration via MCF is recommended when two or more users need to make changes to the configuration. Although in cases of conflict, MCF sharing provides a Physical Mismatch Resolution dialog (see How to resolve physical mismatches in a shared configuration), the respective tasks of the users should be carefully planned and agreed upon. This eases later mismatch resolutions.

The local configuration file and the master configuration file both carry a timestamp to allow HCM to detect changes done to non-IODF objects. Resynchronization and physical mismatch resolution is then based both on the LC flag and the various timestamps: the MCF physical timestamps, timestamps of the local configuration and on the IODF timestamp.

Using the HCD profile keyword MCF_VOL lets you specify a volume serial number where to store the MCF on the host (refer to the z/OS HCD User's Guide).

Here is an outline of the MCF mode of operation:

• If you work in connected mode, the MCF is updated and stored on the host whenever you close your configuration.
• If you work in stand-alone mode, you work on a local copy of your configuration. HCM cannot synchronize with the host-based MCF immediately, but sets a so-called LC flag, indicating that the configuration was locally changed.
• During Open configuration processing, HCM compares the timestamps of the local configuration and the master configuration and distinguishes the following scenarios:
  • If the timestamps of the local and the master configuration are the same, your configuration is opened as usual.
  • If the local configuration is older than the MCF, and no local changes (no LC flag) are found in the configuration, then, after the user's confirmation, HCM overwrites the local configuration by downloading the MCF from the host. This ensures, that logical changes to the IODF and physical changes to the MCF are propagated to the current user.
  • If HCM encounters the LC flag to be set, then the following cases are distinguished:
    1. Timestamps of MCF and local configuration are the same:

       This is the case, if a user had accessed the MCF in connected mode and ended the session with MCF, local configuration and IODF in sync. Later, the same user has updated the local configuration in stand-alone mode. Even later again, the same user accesses the configuration in connected mode, without any other user having accessed the configuration in the meantime. Opening processing continues as usual and only at closing time of the configuration, HCM updates the MCF on the host with all of the user's changes (from the previous stand-alone and the current connected session).

    2. Timestamps of MCF and local configuration are different:

       This is the case, if another user has accessed the MCF in connected mode. In this case, HCM opens the Physical Mismatch Resolution to let the current user resolve physical mismatches due to the changes in his local configuration.