text: **Redundant storage area network**
  A redundant SAN is a SAN configuration in which there is no single point of failure (SPOF). 
  Therefore, data traffic continues no matter what component fails. Connectivity between the 
  devices within the SAN is maintained (although possibly with degraded performance) when 
  an error occurs. A redundant SAN design is normally achieved by splitting the SAN into two 
  independent counterpart SANs (two SAN fabrics). In this configuration, if one path of the 
  counterpart SAN is destroyed, the other counterpart SAN path keeps functioning. 
  
  **Relationship**
  In Metro Mirror or Global Mirror, a relationship is the association between a master volume 
  and an auxiliary volume. These volumes also have the attributes of a primary or secondary 
  volume. 
  
  **Reliability, availability, and serviceability**
  Reliability, availability, and serviceability (RAS) are a combination of design methodologies, 
  system policies, and intrinsic capabilities that, when taken together, balance improved 
  hardware availability with the costs that are required to achieve it. 
  
  Reliability is the degree to which the hardware remains free of faults. Availability is the ability 
  of the system to continue operating despite predicted or experienced faults. Serviceability is 
  how efficiently and nondisruptively broken hardware can be fixed. 