text: **11.6.10 Global Mirror overview**
  
  This section describes the Global Mirror copy service, which is an asynchronous remote copy 
  service. This service provides and maintains a consistent mirrored copy of a source volume to 
  a target volume. 
  
  Global Mirror function establishes a Global Mirror relationship between two volumes of equal 
  size. The volumes in a Global Mirror relationship are referred to as the*master*(source) 
  volume and the*auxiliary*(target) volume, which is the same as Metro Mirror. Consistency 
  groups can be used to maintain data integrity for dependent writes, which is similar to 
  FlashCopy Consistency Groups. 
  
  Global Mirror writes data to the auxiliary volume asynchronously, which means that host 
  writes to the master volume provide the host with confirmation that the write is complete 
  before the I/O completes on the auxiliary volume. 
  
  Global Mirror has the following characteristics: 
  
  (cid:2) Near-zero RPO 
  (cid:2) Asynchronous 
  (cid:2) Production application performance that is affected by I/O sequencing preparation time 
  
  **Intracluster Global Mirror**
  Although Global Mirror is available for intracluster, it has no functional value for production 
  use. Intracluster Metro Mirror provides the same capability with less processor use. However, 
  leaving this functionality in place simplifies testing and supports client experimentation and 
  testing (for example, to validate server failover on a single test system). As with Intracluster 
  Metro Mirror, you must consider the increase in the license requirement, because source and 
  target exist on the same IBM Spectrum Virtualize system. 