Network changes on a vSAN cluster with out impacting vSAN storage

Products

• VMware vSAN

Issue/Introduction

Attempting to make a network change to a vSAN cluster's vSAN network with out impacting vSAN storage

Environment

vSAN (All versions) 

Cause

vSAN depends on a consistent network connections to provide storage, 
Changes and maintenance to the vSAN network can cause an interruption to the network connection between hosts and impact storage. 

Resolution

When preforming network changes on a vSAN host we would want to always proceed one host at a time using maintenance mode.

Confirm with your physical networking team that the settings or change is correctly configured and will not disrupt traffic after it is made. 
Review the vSAN cluster health check and make sure there are no outstanding alarms. 

1. Navigate to the vSAN cluster.
2. Click the Monitor tab.
3. Under vSAN, select Skyline Health to review the vSAN health finding.
4. Under Health findings, perform the following:
   - Click Unhealthy to view the issues and the details. Click Troubleshoot to troubleshoot and fix an issue. You can sort the findings by root cause to resolve the primary issues and then verify if the impacted issues can be resolved.
   - Click View History Details to identify the status history of the health finding for a particular time period. The default time period is 24 hours. You can also customize the time period as per your requirement. The status of an unhealthy finding is displayed in yellow or red. Click the Ask VMware button to open a knowledge base article that describes the health finding and provides information about how to resolve the issue. You can also view the status history of the health finding for a given period using History Details tab.

Place the first host in to maintenance mode - we would advise if possible and the resources are available to use full data evacuation for this first host

• Right-click the host and select Maintenance Mode > Enter Maintenance Mode.
• Select a data evacuation mode and click OK.

Once in maintenance mode preform any planned network changes that would impact only this host then review the vSAN cluster health check once more and confirm there are no alarms. 
Pay specific attention to network related alarms. 

Once complete remove the first host from maintenance mode and check the vSAN cluster health once more. If the cluster health shows no issues you can move to the second host. 
If there are any issues seen after the network change, these would need to be addressed and may be caused by incorrect network settings or an issue with the physical network. 

Repeat the same process for each host one at a time including reviewing the vSAN cluster health.
If the change presented no issues for the first host it may now be beneficial to use insure accessibility vs full data migration. 
This chose would be up to the administrator and owner of the data stored in vSAN. 


In some cases a network change that will disconnect the hosts from each other until the full change is made to all hosts is required. 
For these situations it may be beneficial to schedule a maintenance window to Shut Down the vSAN Cluster Using the Shutdown Cluster Wizard