text: **FlashCopy indirection layer**
  The*FlashCopy indirection layer*governs the I/O to the source and target volumes when a 
  FlashCopy mapping is started, which is done by using the FlashCopy bitmap. The purpose of 
  the FlashCopy indirection layer is to enable the source and target volumes for read and write 
  I/O immediately after the FlashCopy is started. 
  
  The indirection Layer intercepts any I/O coming from a host (read or write operation) and 
  addressed to a FlashCopy volume (source or target). It determines whether the addressed 
  volume is a source or a target, its direction (read or write), and the state of the bitmap table for 
  the FlashCopy mapping that the addressed volume is in. It then decides what operation to 
  perform. Hereunder are the different I/O indirections. 