difference of PP/VE and VMware NMP Round Robin

EMC PowerPath/VE provides significant enhancements over the VMware’s native multipathing, including:

• PowerPath/VE enhances the redundant infrastructure created by Storage Administrators
  
  • Round Robin  algorithms (i.e. VMware NMP)will use all the paths; however, they don’t use those paths intelligently and efficiently
    
• PowerPath/VE provides intelligent path routing with optimized load balancing policies for EMC and non-EMC arrays
  
  • With Symmetrix Optimization and CLARiiON Optimization policies, PowerPath/VE considers the number of I/Os, size of I/Os, type of I/Os, queuing delay, latency of recent I/Os, and throughput of I/Os when making a routing decision
    
  • There are eight policies in total
    

• PowerPath/VE provides intelligent path testing of idle and dead paths

  
  
  • Path testing is load based.  A busier system with more I/O completions requires less testing
    
  • Testing idle paths to a device ensure I/O success when the application begins driving I/O
    
  • Testing dead paths will return them to use quickly
    
• PowerPath/VE provides advanced path failover by proactively shifting I/O load to known viable paths for hosts sharing a common path when a failure occurs
  
• Minimizes administrator cycles since no configuration is required.  PowerPath/VE automatically recognizes the array type and configures the optimized load balancing and failover policies without the need for administrator intervention
  

• PowerPath/VE provides advanced path management and monitoring

  • Deeper integration with vCenter StorageViewer providing path state details
    
  • Centralized management of PowerPath/VE for vSphere hosts using a remote version of the powermt CLI
    
  • Path latency monitoring measures the I/O completion time on all HBA paths and provides a user-settable threshold monitor.  This aids Storage Administrators in determining whether an application issue is a result of failing SAN paths
    
• PowerPath/VE responds to decaying paths (paths that have not entirely failed) by redistributing some of the I/O to healthier paths