text: **11.6.3 Importance of write ordering**
  
  Many applications that use block storage have a requirement to survive failures, such as loss 
  of power or a software crash, and to not lose data that existed before the failure. Because 
  many applications must perform large numbers of update operations in parallel, maintaining 
  write ordering is key to ensure the correct operation of applications after a disruption. 
  
  An application that performs many database updates is designed with the concept of 
  dependent writes. With dependent writes, it is important to ensure that an earlier write 
  completed before a later write is started. Reversing or performing the order of writes 
  differently than the application intended can undermine the application’s algorithms and can 
  lead to problems, such as detected or undetected data corruption. 
  
  The IBM Spectrum Virtualize Metro Mirror and Global Mirror implementation operates in a 
  manner that is designed to always keep a consistent image at the secondary site. The Global 
  Mirror implementation uses complex algorithms that identify sets of data and number those 
  sets of data in sequence. The data is then applied at the secondary site in the defined 
  sequence. 
  
  Operating in this manner ensures that if the relationship is in a Consistent_Synchronized 
  state, the Global Mirror target data is at least crash consistent, and supports quick recovery 
  through application crash recovery facilities. 