Usually, each process performs a checkpoint operation after a
    certain set of thresholds has been exceeded. The RMU Checkpoint
    command allows you to spontaneously force each process to perform
    a checkpoint operation.

    Performing a checkpoint operation is useful for several purposes.
    A checkpoint operation with the Wait qualifier causes all updated
    database pages to be flushed to disk. A checkpoint operation
    also improves the redo performance of the database recovery (DBR)
    process (although the per-process parameters should have already
    been properly initialized with this goal in mind).

    When the Checkpoint command with the Wait qualifier completes
    (the system prompt is returned), all active processes have
    successfully performed a checkpoint operation.

    When the system prompt is returned after you issue the Checkpoint
    command with the Nowait qualifier, there is no guarantee that
    all active processes have successfully performed a checkpoint
    operation.