Managing VPGs : Editing a VPG : Modifying the Journal Size Hard Limit
  
Modifying the Journal Size Hard Limit
If the journal size hard limit is reduced, and if the current size is greater than the newly defined size, the journal remains at the current size. When the amount of the journal used falls below the hard limit value it will not grow greater than the new hard limit. Unused journal volumes from the added volumes are marked for removal and removed after the time equivalent to three times the amount specified for the journal history, or twenty-four hours, whichever is more.
Note: If the Journal Size Hard Limit or Journal Size Warning Threshold in the VPG SLA settings are changed, the changed values are not applied to existing virtual machines but only to new virtual machines added to the VPG.