Configuring vSAN Unicast networking from the command line-HQY 一个和谐有爱的空间

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Configuring vSAN Unicast networking from the command line

https://knowledge.broadcom.com/external/article?legacyId=2150303

Configuring vSAN Unicast networking from the command line

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Article ID: 326427

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Updated On: 06-06-2024

Products

VMware vSAN

Issue/Introduction

This article provides step-by-step instructions on how to manually configure vSAN Unicast networking from esxcli.

Note: vSAN Unicast mode is a feature that was introduced in vSAN 6.6 (vSphere 6.5.0d)
Unicast replaced legacy multicast networking in order to simplify the network requirements of maintaining a vSAN cluster's Quorum.

Symptoms:

1. Occasionally when upgrading vSAN Clusters to vSphere 6.5.0d or later, one or more hosts may fail to inherit the Cluster Member Updates from vCenter.

2. In some cases, the list of vSAN nodes maintained by vCenter and the number of actual nodes may differ due to nodes being added or removed while vCenter was unavailable.

Environment

VMware vSAN 8.x

VMware vSAN 7.x
VMware vSAN 6.7.x
VMware vSAN 6.6.x

Resolution

You can use the following steps to manually rebuild the Unicast agent list on each host:

1. Identifying necessary vSAN Cluster information.
2. Building the vSAN Unicast agent list.
3. Last Steps.

1. Identify the VMkernel port used for vSAN, its IP address, and the node UUID on each host in the cluster.

1.1 SSH to every ESXi host in the cluster and login as root.

1.2 Run the following command to identify the VMkernel port used for vSAN, and copy the output for later use:

esxcli vsan network list

Note: The IP address of vmk2 on this host is: 172.16.15.11

1.4 Find the node UUID of the host with the following command:

cmmds-tool whoami

2.2 Sometimes, there might be incorrect entries in a host's Unicast agent list such as:

"Supports Unicast" is set to False for a particular host, an incorrect IP address, an incorrect Node UUID, or a host which is NOT a Stretched Cluster Witness host is incorrectly marked with "IsWitness" as True.

An existing entry cannot be modified. It must be deleted and re-added.

2.2.1 Check the current unicast agent list with the following command

esxcli vsan cluster unicastagent list

Note: In the output above, the unicast agent list was cleared out.

2.3 Add entries to the unicast agent list

**REMINDER** When building the Unicast agent list on an ESXi host, add entries for all the other hosts but never add the IP of the host whose table is being configured.

When an ESXi host has its own IP address in its Unicast agent list, vSAN can go unstable, networking problems can arise and potentially lead to the host encountering a PSOD.

Using the 3 node example, each host will have 2 entries.

Data Node entry syntax:

esxcli vsan cluster unicastagent add -t node -u <Host_UUID> -U true -a <Host_VSAN_IP> -p 12321

Example on host 1

3.2 After all the process has been completed successfully, make sure to enable the "Cluster Member List Updates" again on all the nodes in the cluster. Run the following command:

esxcfg-advcfg -s 0 /VSAN/IgnoreClusterMemberListupdates

Additional Information

If you find that you have completed your upgrade to vSAN 6.6 including the on-disk upgrade process and your hosts are still utilizing multicast for cluster communications, confirm that you do not have an orphaned/dead host information stuck in cmmds as this can prevent the conversion from occurring naturally.

VMware does not support reverting back to multicast mode after the vSAN 6.6 installation or upgrade has completed and unicast mode has been successfully configured.

Impact/Risks:

Network partitioning is a risk if the Unicast agent list is not properly rebuilt. In most situations, the vSAN cluster has already formed multiple partitions. The goal of rebuilding the table is to form one vSAN cluster.

Note: When building a Unicast agent list on an ESXi host, add entries for all the other hosts, but never add the IP of the host whose table is being configured.

When a vSAN Data Node or Witness Node has its own IP address in its Unicast agent list, many networking problems can arise and could lead to a PSOD.

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