ESXi hosts status is Unknown in NSX UI due to opsAgent crash

Products

• VMware NSX

Issue/Introduction

• NSX UI shows ESXi hosts with status Unknown.
• Affected ESXi hosts created opsAgent zdump files: /var/core/opsAgent-zdump.###
• During heavy load, multiple ESXi hosts may be affected in batches.
• The zdump content shows that boost::uuids::random_generator()() throws an exception boost::uuids::entropy_error

Environment

VMware NSX 9.x
VMware NSX 4.x
VMware NSX-T Data Center 3.x

Cause

This issue may occur if ESXi host entropy is exhausted on the ESXi host.

Resolution

This is a known issue impacting VMware NSX.

Workaround:

• To recover the connection on the ESXi host:

  /etc/init.d/nsx-opsagent restart

• To reduce the probabilty of the issue reoccuring:
  • Inspect the sources configured to provide entropy:

    esxcli system settings kernel list -o entropySources

  • Enable additional and/or tune the sources of entropy.
    Please refer to the ESXi documentation: Controlling ESXi Entropy
    For example, to enable all sources:

    esxcli system settings kernel set -s entropySources -v 0xF 

    Or, to enable interrupts and the entropyd daemon (1+8):

    esxcli system settings kernel set -s entropySources -v 9

    Note: A reboot is required for the ESXi host to use the adjusted configuration.