vDS MTU change results in storage or network disruption

Products

• VMware vSphere ESXi

Issue/Introduction

• The MTU value configured on vDS has been changed
• Network based storage reports loss of access errors like this example
  
  "Lost access to volume <volume identifier> due to connectivity issues. Recovery attempt is in progress and outcome will be reported shortly."
  
  
• There may be reports of brief network disruption for VMs
• ESXi logs show NIC down/up events in /var/run/log/vobd.log similar to this example
  
  <DATE>T18:13:17.205Z: [netCorrelator] 4565695060272us: [vob.net.vmnic.linkstate.down] vmnic vmnic0 linkstate down
<DATE>T18:13:17.609Z: [netCorrelator] 4565694464829us: [vob.net.vmnic.linkstate.down] vmnic vmnic1 linkstate down

<DATE>T18:13:20.158Z: [netCorrelator] 4565697014473us: [vob.net.vmnic.linkstate.up] vmnic vmnic0 linkstate up
<DATE>T18:13:20.993Z: [netCorrelator] 4565697848799us: [vob.net.vmnic.linkstate.up] vmnic vmnic1 linkstate up

Environment

vSphere Networking

Cause

When the MTU value configured on vDS is changed, a link reset, down/up, is performed by design.
This is required so that buffers can be reconfigured and reallocated.
Some brief interruption to networking will result.

Resolution

This is expected behaviour.