ESXi Host Status Unknown in vLCM due to BIOS to UEFI Migration or Boot Media Inaccessibility

Products

• VMware vSphere ESXi

Issue/Introduction

• The ESXi host status shows as 'unknown' in vSphere Lifecycle Manager (vLCM) after remediation or during a compliance check.
• Compliance check fails with the error: An unknown error occurred while performing the operation.
• A "Legacy boot detected" warning was previously displayed, or the host was recently migrated from Legacy BIOS to UEFI mode.
• iSCSI storage connectivity is lost or intermittent on Cisco UCS hardware following BIOS changes.

Environment

• VMware vSphere ESXi 7.x / 8.x
• VMware vCenter Server 7.x / 8.x
• Cisco UCS Hardware (B-Series or C-Series)

Resolution

• Verify Cisco UCS Settings:
  • Enable Consistent Device Naming (CDN) in the BIOS policy to ensure NIC and iSCSI device naming remains consistent across boot mode changes.
• Verify Communication:
  • SSH to the ESXi host and test connectivity to vCenter on port 9084: `nc -zv <vCenter_FQDN> 9084`.
  • Ensure the vCenter FQDN is correctly listed in `/etc/hosts`.
• Validate Boot Media Integrity:
  • Run ls -l / and check if bootbank and altbootbank symlinks point to valid directories.
  • If symlinks are broken following a BIOS-to-UEFI migration, you must perform a clean reinstallation of ESXi to ensure the correct GPT partition table and UEFI boot partition are created.
  • Download the appropriate ESXi installer from the Broadcom Support Portal.
• Inventory Refresh:
  • Disconnect and reconnect the ESXi host in the vCenter Inventory to refresh the management agent state.

Additional Information

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