Check vSAN VMkernel configuration
Verify that every participating host has the intended VMkernel adapter enabled for vSAN traffic and that the correct network is attached.
Check end-to-end reachability
Test host-to-host communication over the vSAN network. Validate VLAN configuration, MTU and physical uplinks rather than testing only management connectivity.
Look for packet loss
Packet loss and timeouts can cause heartbeat failures and cluster partitions. Check switch counters, NIC errors and physical links when the symptom is intermittent.
Check membership changes
Use esxcli vsan cluster get and vSAN health information to determine whether hosts are repeatedly joining and leaving the cluster.
Review vmkernel and vobd logs
Look for network-card errors, heartbeat timeouts and communication failures around the exact incident time.
Validate the physical network
Check the switch ports, VLANs, LACP configuration if used, MTU consistency and redundancy. vSAN depends on reliable host-to-host communication.
Confirm recovery
After correcting the network, verify vSAN health, cluster membership and object accessibility before closing the incident.
Useful commands
esxcli vsan cluster get
vmkping -I vmkX <peer-vSAN-IP>
esxcli network nic list
esxcli network nic stats get -n vmnicXMore VMware troubleshooting
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