text: If multiple writes are allowed to be applied to the master for a sector, only the most recent 
  write gets the correct data during reconstruction. If reconstruction is interrupted for any 
  reason, the intermediate state of the auxiliary is inconsistent. Applications that deliver such 
  write activity do not achieve the performance that Global Mirror is intended to support. A 
  volume statistic is maintained about the frequency of these collisions. 
  
  An attempt is made to allow multiple writes to a single location to be outstanding in the Global 
  Mirror algorithm. There is still a need for master writes to be sequential, and the intermediate 
  states of the master data must be kept in a non-volatile journal while the writes are 
  outstanding to maintain the correct write ordering during reconstruction. Reconstruction must 
  never overwrite data on the auxiliary with an earlier version. The volume statistic that is 
  monitoring colliding writes is now limited to those writes that are not affected by this change. 
  
  Figure 11-91 shows a colliding write sequence example. 