vSphere discovery fails with NFS error

If, when attempting to discover your vSphere environment, an error is displayed that relates to NFS datastores, it could be that the maximum amount of NFS datastores (8 by default) have already been mounted on each ESXi host.

In order to increase the limit, the following values must be set in the host advanced options.

To edit advanced configuration options, select the ESXi/ESX host in the Inventory Panel, then navigate to Configuration > Software > Advanced Settings to launch the Settings window.

Set these values:

  • Under NFS, Select NFS.MaxVolumes: Limits the number of NFS datastores which can be mounted by the vSphere ESXi/ESX host concurrently. The default value is 8, and can be increased to a maximum specific to the version of ESXi/ESX:

    • ESXi/ESX 3.x: Set NFS.MaxVolumes to 32
    • ESXi/ESX 4.x: Set NFS.MaxVolumes to 64
    • ESXi 5.0/5.1/5.5: Set NFS.MaxVolumes to 256
    • ESXi 6.0: Set NFS.MaxVolumes to 256
  • Under Net, Select Net.TcpipHeapSize: The amount of heap memory, measured in megabytes, which is allocated for managing VMkernel TCP/IP network connectivity. When increasing the number of NFS datastores, increase the default amount of heap memory as well:

    • ESXi/ESX 3.x: Set Net.TcpipHeapSize to 30
    • ESXi/ESX 4.x: Set Net.TcpipHeapSize to 32
    • ESXi 5.0/5.1/5.5: Set Net.TcpipHeapSize to 32
    • ESXi 6.0: Set Net.TcpipHeapSize to 32
  • Under Net, Select Net.TcpipHeapMax: The maximum amount of heap memory, measured in megabytes, which can be allocated for managing VMkernel TCP/IP network connectivity. When increasing the number of NFS datastores, increase the maximum amount of heap memory as well, up to the maximum specific to the version of ESXi/ESX host:

    • ESXi/ESX 3.x : Set Net.TcpipHeapMax to 120
    • ESXi/ESX 4.x: Set Net.TcpipHeapMax to 128
    • ESXi 5.0/5.1: Set Net.TcpipHeapMax to 128
    • ESXi 5.5: Set Net.TcpipHeapMax to 512
    • ESXi 6.0: Set Net.TcpipHeapMax to 1536

Notes:

  • These settings enable the maximum number of NFS mounts for vSphere ESXi/ESX.
  • Changing Net.TcpipHeapSize and/or Net.TcpipHeapMax requires a host reboot for the changes to take effect.