vSAN Node is in Cluster Partitioned state and there is also vSAN MTU issue Health Alarm in vSAN Skyline health.
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vSAN Node is in Cluster Partitioned state and there is also vSAN MTU issue Health Alarm in vSAN Skyline health.

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Article ID: 326579

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Updated On:

Products

VMware vSAN

Issue/Introduction

Symptoms:

  • The cluster is partitioned, with the affected node not able to communicate via ping with other data nodes.

    [root@esxi1:~] vmkping -I vmk2 -d -s 8972 10.X.X.10;
    PING 10.X.X.10 (10.X.X.10): 8972 data bytes

    --- 10.X.X.10 ping statistics ---
    3 packets transmitted, 0 packets received, 100% packet loss

    In above example the vSAN node is configured with MTU 9000 hence we are using MTU value of 8972 for vmkping to test network connectivity with another vSAN node.

    Refer KB # vSAN skyline health reports errors:vSAN: MTU check (ping with large packet size)

  • One or more vSAN nodes are in Cluster partitioned state and this can be validated by checking the ' esxcli vsan cluster get' Output where the member count is in reduced value when compared to actual member count value of the vSAN Cluster. 

    Example : 

    esxi1# esxcli vsan cluster get
    Cluster Information
       Enabled: true
       Current Local Time: 2019-09-03T07:02:40Z
       Local Node UUID: ########-####-####-####-########7c0e
       Local Node Type: NORMAL
       Local Node State: MASTER
       Local Node Health State: HEALTHY
       Sub-Cluster Master UUID: ########-####-####-####-########7c0e
       Sub-Cluster Backup UUID:
       Sub-Cluster UUID: ########-####-####-####-########2f67
       Sub-Cluster Membership Entry Revision: 0
       Sub-Cluster Member Count: 1
       Sub-Cluster Member UUIDs: ########-####-####-####-########7c0e
       Sub-Cluster Member HostNames: NODE2
       Sub-Cluster Membership UUID: ########-####-####-####-########7c0e
       Unicast Mode Enabled: true
       Maintenance Mode State: OFF
       Config Generation: ########-####-####-####-########9e01 12 2019-08-19T09:12:12.1

  • Virtual machines hosted on the affected node become inaccessible or unreachable.

  • In some cases, there would be intermittent ping loss within the vSAN cluster.

  • vSAN: MTU check (ping with large packet size) alert along with vSAN Cluster partition alarm is also noticed in vSAN skyline health indicating there is a ongoing network issue.

  • vSAN skyline health reports multiple errors as shown in the below screenshot: 

    • vSAN: Basic (unicast) connectivity check
    • VSAN: MTU check (ping with large packet size)
    • vSAN cluster partition
    • vSAN object health
    • vMotion: Basic (unicast) connectivity check
    • vMotion: MTU check (ping with large packet size)

Environment

VMware vSAN (All Versions)

Cause

  • The NIC entered a hung state despite running the latest driver.

  • If vSAN vmkernel adapters are configured with IPs in different subnets, routing tables must be in place to allow traffic between subnets.

  • Missing or incorrect routing entries at the switch side, or firewall rule updates affecting the ESXi host, can also block ping communication and result in host partitioning.

  • Uplink failure can also result vSAN Network partition issue.

Resolution

Step 1: Verify Network Health 
 
If the underlying network issue affecting vSAN nodes is resolved, both the vSAN cluster partition and MTU-related issues should automatically clear without further intervention.

Step 2: Proceed with Additional Checks (if issue persists)  
If the network problem is not yet resolved, continue with the following checks:

1: vmkping test to check vSAN network connectivity issue. 
Packets get dropped upon ping to VSAN vmkernel.

NODE2# vmkping -I vmk2 192.168.x.xxx -c 1000
PING 192.168.x.xxx (192.168.x.xxx): 56 data bytes
64 bytes from 192.168.x.xxx: icmp_seq=2 ttl=64 time=0.133 ms
64 bytes from 192.168.x.xxx: icmp_seq=3 ttl=64 time=0.111 ms
64 bytes from 192.168.x.xxx: icmp_seq=4 ttl=64 time=0.129 ms
64 bytes from 192.168.x.xxx: icmp_seq=5 ttl=64 time=0.133 ms
64 bytes from 192.168.x.xxx: icmp_seq=6 ttl=64 time=0.137 ms
64 bytes from 192.168.x.xxx: icmp_seq=7 ttl=64 time=0.140 ms
64 bytes from 192.168.x.xxx: icmp_seq=8 ttl=64 time=0.141 ms
64 bytes from 192.168.x.xxx: icmp_seq=9 ttl=64 time=0.127 ms
64 bytes from 192.168.x.xxx: icmp_seq=10 ttl=64 time=0.139 ms
64 bytes from 192.168.x.xxx: icmp_seq=11 ttl=64 time=0.087 ms<======= Sequence missed
64 bytes from 192.168.x.xxx: icmp_seq=37 ttl=64 time=0.137 ms<======= Sequence missed
64 bytes from 192.168.x.xxx: icmp_seq=38 ttl=64 time=0.151 ms

2: Packet Capture Analysis to validate if there is any underlying network issue. 

Packet capture shows UDP traffic is working but  We have seen the "sequence 11 is followed by sequence 37" 

# pktcap-uw --uplink vmnic4 --dir 0 --stage 1 --proto 0x11 -o -| tcpdump-uw -r - -nne   >> Run this command on one of the data node where uplink 4 is used for vSAN vmkernel.

----- Output of the above command is as below  -----
The Stage is Post.
The session filter IP protocol is 0x11.
pktcap: The output file is -.
pktcap: No server port specifed, select 21248 as the port.
pktcap: Local CID 2.
pktcap: Listen on port 21248.
reading from file -, link-type EN10MB (Ethernet)
pktcap: Accept...
pktcap: Vsock connection from port 1029 cid 2.

07:39:15.068063 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 178: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 136
07:39:16.068090 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 178: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 136
07:39:17.068136 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 258: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 216
07:39:17.068162 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 186: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 144
07:39:18.068157 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 258: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 216
07:39:18.068186 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 186: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 144
07:39:19.068208 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 242: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 200
07:39:20.068203 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 242: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 200
07:39:21.068238 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 242: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 200
07:39:22.068288 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 242: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 200
07:39:23.068326 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 242: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 200
07:39:24.068347 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 242: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 200
07:39:25.068365 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 242: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 200
07:39:26.068417 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 242: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 200
07:39:27.068432 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 466: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 424
07:39:28.068511 ##:##:##:##:##:90 > ##:##:##:##:##:93, ethertype IPv4 (0x0800), length 466: 192.168.x.xxx.12321 > 192.168.x.xxx.12321: UDP, length 424

The same packet capture with ICMP filter shows more drops:

# pktcap-uw --uplink vmnic5 --dir 0 --stage 0 --proto 0x01 -o -|tcpdump-uw -r - -nne
The name of the uplink is vmnic5.
The Stage is Pre.
The session filter IP protocol is 0x01.
pktcap: The output file is -.
pktcap: No server port specifed, select 42606 as the port.
pktcap: Local CID 2.
pktcap: Listen on port 42606.
reading from file -, link-type EN10MB (Ethernet)
pktcap: Accept...
pktcap: Vsock connection from port 1026 cid 2.

07:45:06.559790 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 98, length 64
07:45:07.561992 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 99, length 64
07:45:08.562521 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 100, length 64
07:45:09.564725 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 101, length 64
07:45:10.566928 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 102, length 64
07:45:11.569107 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 103, length 64
07:45:27.598571 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx >  192.168.x.xxx: ICMP echo request, id 36438, seq 119, length 64 <======== show sequence missed again.
07:45:28.600526 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 120, length 64
07:45:29.602738 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 121, length 64
07:45:30.604959 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 122, length 64
07:45:31.607195 ##:##:##:##:##:93 > ##:##:##:##:##:90, ethertype IPv4 (0x0800), length 98: 192.168.x.xxx > 192.168.x.xxx: ICMP echo request, id 36438, seq 123, length 64

NODE2# esxcli network ip interface ipv4 get
Name  IPv4 Address   IPv4 Netmask     IPv4 Broadcast  Address Type  Gateway        DHCP DNS
----  -------------  ---------------  --------------  ------------  -------------  --------
vmk0  10.12.xxx.xxx  255.xxx.xxx.xxx  10.12.xxx.255     STATIC        10.12.xxx.xxx     false
vmk2  192.168.x.xxx  255.xxx.xxx.x    192.168.xxx.255   STATIC        0.0.0.0           false
vmk3  192.168.x.xx   255.xxx.xxx.0    192.168.xxx.255   STATIC        0.0.0.0           false

NODE1# esxcli network ip interface ipv4 get
Name  IPv4 Address   IPv4 Netmask     IPv4 Broadcast  Address Type  Gateway        DHCP DNS
----  -------------  ---------------  --------------  ------------  -------------  --------
vmk0  10.12.xxx.xxx  255.255.xxx.xxx   10.xx.xxx.255   STATIC         10.12.xxx.xxx     false
vmk2  192.168.x.xxx  255.255.xxx.xxx   192.168.x.xxx   STATIC        0.0.0.0           false
vmk3  192.168.x.xx   255.255.xxx.xxx   192.168.x.xxx   STATIC        0.0.0.0           false

Isolating 1 NIC shows 100 % packet loss:

NODE2# esxcli network nic list
Name    PCI Device    Driver   Admin Status  Link Status  Speed  Duplex  MAC Address         MTU  Description
------  ------------  -------  ------------  -----------  -----  ------  -----------------  ----  -----------------------------------------------------------------
vmnic0  0000:18:##.##  ntg3     Up            Up            1000  Full    ##:##:##:##:##:0c  1500  Broadcom Corporation NetXtreme BCM5720 Gigabit Ethernet
vmnic1  0000:18:##.##  ntg3     Up            Down             0  Half    ##:##:##:##:##:0d  1500  Broadcom Corporation NetXtreme BCM5720 Gigabit Ethernet
vmnic2  0000:19:##.##  ntg3     Up            Up            1000  Full    ##:##:##:##:##:0e  1500  Broadcom Corporation NetXtreme BCM5720 Gigabit Ethernet
vmnic3  0000:19:##.##  ntg3     Up            Down             0  Half    ##:##:##:##:##:0f  1500  Broadcom Corporation NetXtreme BCM5720 Gigabit Ethernet
vmnic4  0000:87:##.##  qedentv  Down          Down             0  Half    ##:##:##:##:##:2c  1500  QLogic Corp. QLogic FastLinQ QL41xxx 1/10/25 GbE Ethernet Adapter
vmnic5  0000:87:##.##  qedentv  Up            Up           10000  Full    ##:##:##:##:##:2d  1500  QLogic Corp. QLogic FastLinQ QL41xxx 1/10/25 GbE Ethernet Adapter
NODE2#vmkping -I vmk2 192.168.x.xxx -c 100 -i 0.005
PING 192.168.x.xxx (192.168.x.xxx): 56 data bytes

--- 192.168.x.xxx ping statistics ---
100 packets transmitted, 0 packets received, 100% packet loss

Bringing up other NIC and making faulty down show packet is not lost by verifying it on esxtop command and selecting option "n"  to see association between NIC and vmkernel port.

NODE2# esxcli network nic up -n vmnic4

NODE2#esxcli network nic list
Name    PCI Device    Driver   Admin Status  Link Status  Speed  Duplex  MAC Address         MTU  Description
------  ------------  -------  ------------  -----------  -----  ------  -----------------  ----  -----------------------------------------------------------------
vmnic0  0000:18:##.#  ntg3     Up            Up            1000  Full    ##:##:##:##:##:0c  1500  Broadcom Corporation NetXtreme BCM5720 Gigabit Ethernet
vmnic1  0000:18:##.#  ntg3     Up            Down             0  Half    ##:##:##:##:##:0d  1500  Broadcom Corporation NetXtreme BCM5720 Gigabit Ethernet
vmnic2  0000:19:##.#  ntg3     Up            Up            1000  Full    ##:##:##:##:##:0e  1500  Broadcom Corporation NetXtreme BCM5720 Gigabit Ethernet
vmnic3  0000:19:##.#  ntg3     Up            Down             0  Half    ##:##:##:##:##:0f  1500  Broadcom Corporation NetXtreme BCM5720 Gigabit Ethernet
vmnic4  0000:87:##.#  qedentv  Up            Up           10000  Full    ##:##:##:##:##:2c  1500  QLogic Corp. QLogic FastLinQ QL41xxx 1/10/25 GbE Ethernet Adapter
vmnic5  0000:87:##.#  qedentv  Up            Up           10000  Full    ##:##:##:##:##:2d  1500  QLogic Corp. QLogic FastLinQ QL41xxx 1/10/25 GbE Ethernet Adapter

NODE2#esxcli network nic down -n vmnic5

NODE02# vmkping -I vmk2 192.xxx.x.xxx-c 100 -i 0.005
PING 192.168.x.xxx (192.xxx.x.xxx): 56 data bytes
64 bytes from 192.168.x.xxx: icmp_seq=0 ttl=64 time=0.148 ms
64 bytes from 192.168.x.xxx: icmp_seq=1 ttl=64 time=0.069 ms
64 bytes from 192.168.x.xxx: icmp_seq=2 ttl=64 time=0.066 ms
64 bytes from 192.168.x.xxx: icmp_seq=3 ttl=64 time=0.072 ms
64 bytes from 192.168.x.xxx: icmp_seq=4 ttl=64 time=0.068 ms
64 bytes from 192.168.x.xxx: icmp_seq=5 ttl=64 time=0.061 ms

NIC was using latest driver.

NODE2#vmkload_mod -s qedentv
vmkload_mod module information
 input file: /usr/lib/vmware/vmkmod/qedentv
 Version: 3.9.31.2-1OEM.670.0.0.8169922
 Build Type: release
 License: QLogic_Proprietary
 Required name-spaces:
  com.vmware.vmkapi#v2_5_0_0
 Parameters:
Refer KB: Determining Network/Storage firmware and driver version in ESXi

3. If the vSAN network IP addresses are in different subnets, configure manual static routes in the routing table using the below kb article:

   Configuring static routes for vmkernel ports on an ESXi host

Workaround:

         Refer KB # Network adapter (vmnic) is down or fails with a Failed Criteria Code



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