Note that an Enginuity NDU involving the Symmetrix VMAX Series is different to the NDU process of earlier Symmetrix models. There is no cache (track ID) format change during a VMAX NDU. Drive format changes only apply to the older non-VMAX models. Internal metadata will be converted during an Enginuity 5874 to 5875, or Enginuity 5875 to 5876 NDU, the process is quick and entirely non-disruptive. The time required for the "special NDU Fast IML" is the same as required for a VMAX "in-family" Enginuity upgrade. This is in the order of seconds (typically around 5 seconds) and certainly less than 10. On VMAX the FA ports remain online during the NDU. Unlike the older non-VMAX models (detailed above), the FA light is no longer dropped during the special NDU Fast IML step. All attached switches and HBAs remain logged into the Symmetrix VMAX. During the NDU Fast IML all I/O will be paused at the FA layer. Any queued commands or data will resume immediately after the NDU Fast IML step. Links are not bounced, and no I/O is aborted. The EMC-recommended driver and firmware versions and the EMC-recommended host and driver settings should always be set. However, the gathering and analysis of HEAT and EMCGrab outputs (or the use of E-Lab Advisor) before a VMAX NDU is no longer required.
IHAC planned for the In family NDU upgrade.  I have read somewhere that from Enginuity 5875 and later, the light on the FA ports is no longer dropped during the special NDU Fast IML step. Therefore all attached switches and HBAs no longer need to log out and log back in to the Symmetrix. I/O will be paused and queued but will resume immediately after the NDU Fast IML step.  -I would like to check if the 5876 in-family upgrade will still cause any path offline/failover during the FAST IML process?   -Is there a difference for in-family and out-family NDU upgrade in term of the disruption to the FA path?  Many thanks
Will there will be any connectivity issues/path failover & failback during the 
in family code upgrade from 5876.163.105 to 5876.229.145 on VMAX20K ?