vSAN Upgrade when vCenter is hosted on the same vSAN Datastore cluster to be upgraded.

Products

• VMware vSAN

Issue/Introduction

If vCenter is on the same vSAN datastore that belongs to the cluster to be upgraded, then follow these steps before doing upgrade to avoid cluster partitions

This article is intended to assist a vSAN cluster upgrade running on 7.0/8.0 to a higher version on 7.0/8.0. This is not a complete list.

Environment

VMware vSAN 7.0
VMware vSAN 8.0

Resolution

 

SSH to all hosts, login as "root" and run the following command.

Check current value:
# esxcfg-advcfg -g /VSAN/IgnoreClusterMemberListupdates

Run this command to set the value is set to "1"
# esxcfg-advcfg -s 1 /VSAN/IgnoreClusterMemberListupdates

When the upgrade is finished, you can set the value back to the default "0"
# esxcfg-advcfg -s 0 /VSAN/IgnoreClusterMemberListupdates

The above command tells the hosts to "ignore" or stop expecting cluster membership info from vCenter. Instead, the hosts will rely on their own Unicast Agent Lists to determine which cluster they belong to. It ultimately prevents hosts from becoming network partitioned from each other, which would break the cluster.

Tips for upgrading vSAN:

• vCenter should be upgraded first to a higher version and then the witness and then the hosts and the last one would be the disk format versions.
• Witness host must be upgraded with the same ESXi version as the data hosts.
• Do not upgrade the ESXi hosts until the witness is upgraded to maintain backward compatibility

Note: For target version builds below 7.0 (6.7, 6.5, etc) the witness node should be upgraded after upgrading the physical nodes.

Note: Using vSphere Update Manager to upgrade hosts in parallel can result in the witness host being upgraded in parallel with one of the data hosts. To avoid upgrade problems, configure vSphere Update Manager so it does not upgrade the witness host in parallel with the data hosts.

Useful references for vSAN upgrade:

Before you upgrade vSAN 7.0
Before you upgrade vSAN 8.0

VMware vSAN upgrade best practices 
vSAN upgrade requirements

Requirements for enabling vSAN 7.0
Requirements for enabling vSAN 8.0

Upgrading vSAN cluster 7.0  
Upgrading vSAN cluster 8.0

 

Validate hardware for compatibility with these links:

Compatibility Guide
vSAN OSA Nodes  
vSAN ESA ReadyNodes 
vSAN SSD compatibility guide
vSAN I/O controller HCL