text: During the update, each node in your Storwize V7000 clustered system is automatically shut 
  down and restarted by the update process. Because each node in an I/O Group provides an 
  alternative path to volumes, use the Subsystem Device Driver (SDD) to make sure that all I/O 
  paths between all hosts and storage area networks (SANs) work. 
  
  If you do not perform this check, certain hosts might lose connectivity to their volumes and 
  experience I/O errors when the Storwize V7000 node that provides that access is shut down 
  during the update process. You can check the I/O paths by using**datapath query**SDD 
  commands. 
  
  **13.4.2 IBM Storwize V7000 update test utility**
  
  The software update test utility is a Storwize V7000 software utility that checks for known 
  issues that can cause problems during a Storwize V7000 software update. For more 
  information about the utility, see this website. 
  
  Download the software update utility from this page where you can also download the 
  firmware. This procedure ensures that you receive the current version of this utility. You can 
  use the**svcupgradetest**utility to check for known issues that might cause problems during a 
  software update. 