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vSAN host members are not in the same Network Partition Group!!

hello,

i have a cluster of 3 hosts, each one has 1 TB of capacity..

but I can see only 2 TB on the vSANDatastore..

I have noticed that when going to disk management on the vSAN configuration, two host are in a Group 1 (network partition group) and the 3rd is in a Group 2!!

is that normal?

thanks,

regards,

Noura

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admin
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Hi Noura,

The symptoms that you are describing make me think that this can be a Network Multicast Issue.

The quick fix would be to disable igmp snooping on the switch, if this is possible.

You can confirm from the host that is isolated (Group 2) if the VSAN vmk interface sends/receives multicast running this command from the host

tcpdump-uw -i vmk2 -n -s0 -t -c 20 udp port 12345 or udp port 23451

It is expected to see Multicast activity from all the other VSAN hosts if working correctly.

Additional information regarding Multicast Requirements for VSAN can be found here:

Virtual SAN Troubleshooting: Multicast - VMware vSphere Blog

Hope this helps !

NF

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zdickinson
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Good morning, that is not normal.  They should all be in the same network partition.  My guess is that 2 of the nodes can ping the vSAN interfaces and that the third cannot.  Off the top of my head I would check the vLAN tagging.  Thank you, Zach.

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help2help
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hello,

thank yu for your response!

they are all in the same default vlan (no vlan for this VMKernel) and the three vSAN interfaces are pingable... by the vCenter!

regards,

Noura

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admin
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Hi Noura,

The symptoms that you are describing make me think that this can be a Network Multicast Issue.

The quick fix would be to disable igmp snooping on the switch, if this is possible.

You can confirm from the host that is isolated (Group 2) if the VSAN vmk interface sends/receives multicast running this command from the host

tcpdump-uw -i vmk2 -n -s0 -t -c 20 udp port 12345 or udp port 23451

It is expected to see Multicast activity from all the other VSAN hosts if working correctly.

Additional information regarding Multicast Requirements for VSAN can be found here:

Virtual SAN Troubleshooting: Multicast - VMware vSphere Blog

Hope this helps !

NF

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atoerper
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What was your fix for this. We are experiencing the same issue.

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help2help
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Hi,

for that issue the solution is to delete the vSAN's VMkernel and recreate them and check vSAN traffic is selected!

to prevent that you should look for your switch setting as Nelson said in his comment!

regards,

Noura

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