/**
  * Add disk if it does not exist to a given vm
  *
  * @param disk the disk to add
  * @param vmId the ID of the vm to add to if the disk does not exist for this VM
  */
 public static void addDiskToVmIfNotExists(BaseDisk disk, Guid vmId) {
   if (!DbFacade.getInstance().getBaseDiskDao().exists(disk.getId())) {
     addDiskToVm(disk, vmId);
   }
 }
 /**
  * Adds disk to vm
  *
  * @param disk the disk to add
  * @param vmId the ID of the VM to add to
  */
 public static void addDiskToVm(BaseDisk disk, Guid vmId) {
   DbFacade.getInstance().getBaseDiskDao().save(disk);
   VmDeviceUtils.addDiskDevice(vmId, disk.getId());
 }
 /**
  * Adds disk to a VM without creating a VmDevice entry
  *
  * @param disk disk to add
  */
 public static void addDisk(BaseDisk disk) {
   if (!DbFacade.getInstance().getBaseDiskDao().exists(disk.getId())) {
     DbFacade.getInstance().getBaseDiskDao().save(disk);
   }
 }