vSAN Datastore size displayed as 0 bytes and virtual machines are inaccessible

Products

• VMware vSAN

Issue/Introduction

Symptoms:

• Instead of the showing the total size of the vSAN datastore, the host might show only the size of its disk groups on that host.
  If there are no disk groups on that host, host shows vSAN datastore size as 0 Bytes.
  
  # df -h
Filesystem    Size    Used    Available    Use%    Mounted on
vsan          0 B     0 B     0 B          0%      /vmfs/volumes/vSAN_Datastore
  
  
• The Skyline Health section under vSAN Cluster > Monitor > vSAN  reports below errors.
  
  
  • vSAN cluster partition.
  • vSAN: Basic (unicast) connectivity check

• A vSAN host unable to communicate with other hosts in the cluster over the vSAN VMkernel interface configured for vSAN traffic.

# vmkping -I vmkX ##.##.##.## -s 1472 -d

PING server (x.x.x.x) 56(84) bytes of data.
--- server ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 3017ms

 

• This command provides details about which VMKernel is used for vSAN traffic on the ESXi host:

# esxcli vsan network list

Interface
VmkNic Name: vmk3
IP Protocol: IP
Interface UUID: #######-####-####-####-##########
Agent Group Multicast Address: ###.##.##.##
Agent Group IPv6 Multicast Address: ####::#:#:#
Agent Group Multicast Port: 23451
Master Group Multicast Address: #.#.#.#
Master Group IPv6 Multicast Address: ####::#:#:#
Master Group Multicast Port: 12345
Host Unicast Channel Bound Port: 12321
Multicast TTL: 5
Traffic Type: vsan

• "esxtop" command and press "n" will show which active vmnic is being used by the vSAN VMKernel.

Environment

VMware vSAN 7.0.x
VMware vSAN 8.0.x

Cause

The host is unable to communicate with other hosts over the active uplink (physical network adapter) associated with the VMkernel adapter configured for vSAN traffic.

Resolution

Please contact your network team to investigate the host connectivity issues with the remaining hosts in the vSAN cluster using the Active vmnic.

Workaround:

• Bring down the active vmnic, if other active vmnic (vmnicX) is configured.
  "esxcli network nic down -n vmnicX"

Note: Before disabling the active vmnic, please verify the impact of disabling that vmnic.

Additional Information

Troubleshooting the vSAN Network
vSAN skyline health reports errors: vSAN: Basic (unicast) connectivity check and vSAN: MTU check (ping with large packet size)