text: One of the canisters within the system is known as the*configuration node*. This node 
  manages configuration activity for the clustered system. If this node fails, the system 
  automatically nominates another node to become the configuration node. 
  
  Because the active nodes are installed in pairs, each node provides a failover function to its 
  partner node if a node fails. 
  
  **2.5.4 I/O groups**
  
  Within IBM Storwize V7000, 1 - 4 pairs of node canisters are known as*I/O groups*. The IBM 
  Storwize V7000 with installed IBM Spectrum Virtualize supports eight node canisters in the 
  clustered system, which provides four I/O groups. 
  
  When a host server performs I/O to one of its volumes, all the I/Os for a specific volume are 
  directed to the I/O group. Also, under normal conditions, the I/Os for that specific volume are 
  always processed by the same node within the I/O group. 
  
  One node of the I/O group acts as a preferred node for its own specific subset of the total 
  number of volumes that the I/O group presents to the host servers (a maximum of 2048 
  volumes per I/O group). However, each node also acts as a failover node for its partner node 
  within the I/O group, so a node takes over the I/O workload from its partner node, if required, 
  with no effect to the server’s application. 