text: **Clustered system (Storwize V7000)**
  A clustered system, which was known as a cluster, is a group of up to eight IBM Storwize 
  V7000 canisters (two in each system) that presents a single configuration, management, and 
  service interface to the user. 
  
  **Cold extent**
  A cold extent is an extent of a volume that does not get any performance benefit if it is moved 
  from a hard disk drive (HDD) to a Flash disk. A cold extent also refers to an extent that needs 
  to be migrated onto an HDD if it is on a Flash disk drive. 
  
  **Compression**
  Compression is a function that removes repetitive characters, spaces, strings of characters, 
  or binary data from the data that is being processed and replaces characters with control 
  characters. Compression reduces the amount of storage space that is required for data. 
  
  **Compression accelerator**
  A compression accelerator is hardware onto which the work of compression is offloaded from 
  the microprocessor. 
  
  **Configuration node**
  While the cluster is operational, a single node in the cluster is appointed to provide 
  configuration and service functions over the network interface. This node is termed the 
  configuration node. This configuration node manages the data that describes the 
  clustered-system configuration and provides a focal point for configuration commands. If the 
  configuration node fails, another node in the cluster transparently assumes that role. 