text: The next section presents a scenario in which both encryption key providers are enabled at 
  the same time. For more information about how to enable encryption by using only USB flash 
  drives, see 12.4.2, “Enabling encryption using USB flash drives” on page 622. 
  
  For more information about how to enable encryption by using key servers as the sole 
  encryption key provider, see 12.4.3, “Enabling encryption using key servers” on page 627. 
  
  **12.4.2 Enabling encryption using USB flash drives**
  
  **Note:**The system needs at least three USB flash drives to be present before you can 
  enable encryption by using this encryption key provider. IBM USB flash drives are 
  preferred and can be obtained from IBM with the feature name Encryption USB Flash 
  Drives (Four Pack). Other flash drives might also work. You can use any USB ports in any 
  node of the cluster. 
  
  Using USB flash drives as the encryption key provider requires a minimum of three USB flash 
  drives to store the generated encryption keys. Because the system attempts to write the 
  encryption keys to any USB key that is inserted into a node port, it is critical to maintain 
  physical security of the system during this procedure. 