Discrepancy Between ESXi Host and NetApp Storage LIF Connections due to DNS misalignment

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• NetApp Storage reports active traffic and connections on LIF1 and LIF4, while the ESXi host appears to be mounted via LIF3.

  Note: In NetApp storage, a LIF (Logical Interface) is a virtualized network interface that serves as an IP address for data access. It acts as the entry point  for the ESXi host to communicate with the storage volumes.

• Output from esxcli storage nfs41 list shows only a single path (LIF3) configured

  Sample output:

  esxcli storage nfs41 list
Volume Name    Host(s)           Share          Accessible  Mounted  Read-Only  Security    isPE        Hardware Acceleration
  
  ------------- --------------  ------------    ------------  ------   ---------- ---------  ---------    ---------------------

  nfs_vol01     lif3.xxxx.xxxxx   /_nfs_vol01        true      true      false      AUTH_SYS  false        Not Supported

• As per the above output, multipathing is not configured and there are connections only to LIF3

• However, the output of the below command from NetApp storage indicates that there are no connections to LIF3 and all active connections are for LIF1

  network connections active show -lif-name LIF1

Environment

VMware ESX 8.x
VMware ESX 9.x

Cause

The discrepancy in the information seen on the NetApp and the ESXi host is due to a DNS configuration mismatch between the NetApp Storage and the ESXi host.

Cause Validation

The ESXi host is resolving hostnames to IP addresses that do not match the NetApp LIF assignments.

This can be verified using the nslookup command : nslookup <IP/fqdn>

For example, please refer the below table

Interface Name	Storage IP Assignment	ESXi Host Interpretation (DNS)
LIF1	#.#.#.20	#.#.#.10
LIF2	#.#.#.21	#.#.#.11
LIF3	#.#.#.70	#.#.#.20
LIF4	#.#.#.71	#.#.#.21

A comparison of the IP address and interface name, shows that the ESXi host is resolving hostnames to IP addresses that do not match the NetApp LIF assignments. Specifically, the IP address #.#.#.20 is recognized as LIF1 by the NetApp storage, but the ESXi hosts DNS resolution incorrectly identifies that same IP as LIF3.

Because the ESXi host thinks #.#.#.20 is LIF3, it reports the mount point as such. However, the storage controller correctly identifies the incoming traffic on that IP as belonging to LIF1.

Resolution

To resolve the discrepancy and enable proper multipathing, follow these steps:

1. Evacuate Workloads: If other VMFS volumes are available, migrate VMs from the affected NFS volumes to prevent downtime during the reconfiguration.

2. Unmount the NFS 4.1 volumes from the ESXi host.

3. Update the DNS server entries to ensure that FQDNs for LIF1 through LIF4 resolve to the correct IP addresses as defined on the NetApp storage.

4. Perform a nslookup on each LIF FQDN to ensure they point to the correct IPs (e.g., LIF1 : #.#.#.20).

5. Remount the NFS volumes. During the mount process, specify all four hostnames (LIF1, LIF2, LIF3, and LIF4) to enable NFS 4.1 Session Trunking.

6. Run the following command to confirm multiple active paths: esxcli storage nfs41 list