How To Update ESXi Hosts Using VSphere Lifecycle Manager In VCenter: Comprehensive Bare-Metal Patching Guide

Upgrading bare-metal ESXi hypervisors via vSphere Lifecycle Manager (vLCM) inside vCenter Server requires transitioning from legacy baseline patterns to declarative, cluster-wide image specifications. This operational guide outlines the exact workflow for importing software bundles, running pre-remediation compliance checks, and executing rolling, non-disruptive ESXi host upgrades while maintaining cluster high availability. Admins must validate hardware compatibility against the VMware Compatibility Guide and ensure vCenter is updated before altering ESXi host states.

Pre-Upgrade Planning, Compatibility, and Safety Checklists

Before executing any hypervisor upgrades, systems engineers must acknowledge that vCenter Server must always be at a version equal to or higher than the target ESXi host version. Attempting to manage an ESXi host running a newer build than vCenter will result in communication failures, disconnected hosts, and broken cluster services.

Legacy vSphere Update Manager (VUM) baselines are deprecated in newer vSphere branches, making vSphere Lifecycle Manager (vLCM) the industry standard. This modern toolset leverages a declarative "desired state" model, applying a unified image across all hosts in a cluster, including the base ESXi version, vendor add-ons, and firmware packages.

Essential Tools and Infrastructure Requirements

• Administrative Access: Full administrative credentials to vCenter Server (vSphere Client access) with the Lifecycle Cloud Admin or Administrator role.
• vCenter Server Status: vCenter Server appliance updated to the target major version or corresponding patch level.
• Storage Requirements: Minimum of 350 MB of free space in the ESXi boot bank partition, and a configured scratch partition on persistent storage for host log generation during installation.
• Network Access: HTTPS outbound connectivity (Port 443) from vCenter to the VMware Online Depot, or an offline bundle (ZIP) downloaded directly from the VMware Customer Connect portal.
• Active Directory / DNS: Functional forward and reverse DNS resolution for all ESXi hosts and the vCenter Server Appliance.

Operational Prerequisites and Metrics

• vSphere DRS Configuration: Distributed Resource Scheduler (DRS) must be set to Fully Automated to facilitate seamless VM migrations when hosts enter Maintenance Mode.
• vSAN Cluster Health: For vSAN-enabled clusters, confirm all disk groups are healthy, no active resynchronization tasks are running, and the cluster is operating under normal wear-and-tear thresholds.
• Hardware Compatibility (HCL): Validation of server CPU generation, local storage controllers, and network interface cards (NICs) against the VMware Compatibility Guide.
• Upgrade Duration Target: Budget 30 to 45 minutes per ESXi host for software staging, maintenance mode evacuation, host reboot, and post-flight validation.

Step-by-Step ESXi Host Update Execution via vSphere Lifecycle Manager

Step 1: Update vCenter Server to the Target Version

Before touching the ESXi hosts, verify and update the vCenter Server Appliance (VCSA) through the vCenter Server Management Interface (VAMI) at port 5480.

1. Log into the VAMI using root credentials.
2. Navigate to the Update section and click Check Updates.
3. Select the appropriate patch or major release that matches or exceeds your target ESXi host version.
4. Execute the pre-update checks, back up the vCenter database, and run the installation.
5. Confirm the vSphere Client is fully operational after the VCSA reboot before proceeding.

Step 2: Access vSphere Lifecycle Manager and Import Patches

If your vCenter has direct internet connectivity, it automatically synchronizes with the VMware Online Depot. In air-gapped or restricted network environments, you must manually import the offline bundle.

1. Log into the vSphere Client and select the main Menu, then click Lifecycle Manager.
2. If working offline, navigate to the Imported ISOs tab.
3. Click Import ISO and browse to the locally downloaded ESXi installation image (for example, VMware-ESXi-8.0U2-buildnumber-depot.zip).
4. Wait for the upload process to finish and verify the file signature is marked as trusted and valid.

Step 3: Define the Desired State Image for the Cluster

Using cluster-level images enforces consistency across identical hardware platforms, preventing configuration drift.

1. Navigate to the Hosts and Clusters view.
2. Select the target cluster in the inventory tree, click the Updates tab, and choose Image under the Hosts submenu.
3. Click Setup Image to define the state of the cluster.
4. Select the target ESXi Version from the drop-down menu.
5. Click Add-On to select vendor-specific packages (such as HPE Customization, Dell Customization, or Cisco UCS drivers) that correspond to your server vendor.
6. Under the Firmware and Drivers section, integrate hardware management tools (like Dell OpenManage or HPE OneView) if your hardware provider utilizes a Hardware Support Manager (HSM).
7. Click Save to generate the image specification.

Step 4: Run the Compliance and Hardware Compatibility Pre-Checks

Before initiating remediation, Lifecycle Manager must evaluate the cluster to ensure the target hardware supports the image and can safely transition VMs.

1. With the cluster selected, go to Updates, then select Image.
2. Click Check Compliance to compare the current state of each ESXi host against the newly defined desired state.
3. Once completed, click Run Pre-Check to execute an in-depth readiness assessment.
4. Review the generated pre-check report for any blockers, such as incompatible storage controller drivers, insufficient host resources, or virtual machines with mounted local CD-ROM devices.
5. Address any reported issues immediately. Common remediations include unmounting local ISO files from running VMs and temporarily disabling HA Admission Control if cluster resources are constrained.

Step 5: Stage the Update Files to the ESXi Hosts

Staging uploads the required software packages to the local boot devices of the ESXi hosts while they are still online and running active workloads, minimizing the subsequent maintenance window duration.

1. On the cluster Updates page, click the Stage All button, or select individual hosts and click Stage.
2. Confirm the selected components in the staging wizard and click Start Staging.
3. Monitor the progress in the Recent Tasks pane. The host status will transition to Staged once the transmission of binaries is complete.

Step 6: Evacuate Workloads and Remediate the Hosts

Remediation is the actual installation process. If DRS is set to Fully Automated, vCenter will systematically place hosts into Maintenance Mode, migrate active virtual machines to sister hosts in the cluster, apply the image, reboot the host, and bring it back online.

1. Select the first host to be updated or select the entire Cluster parent object for a rolling update.
2. Click Remediate.
3. In the Remediation dialog box, accept the End User License Agreement (EULA).
4. Review the Remediation Settings. Under the Scheduling section, you can configure maintenance mode behavior, VM migration timeouts, and Quick Boot options (if supported by your hardware platform).
5. Click Start Remediation.
6. Watch the vSphere Client inventory. DRS will initiate live vMotion migrations of running VMs to other hosts in the cluster.
7. Once empty, the host enters Maintenance Mode, installs the staged patches, and reboots.

Step 7: Post-Update Host Validation and Verification

After the host reboots, it must be verified before returning to active service.

1. Ensure the host reconnects successfully to vCenter Server.
2. Navigate to the Summary tab of the remediated host and verify the ESXi Version and Build Number match the target image specifications.
3. Verify that local datastores are mounted, network paths are active, and vSAN disk statuses are healthy.
4. Right-click the host and select Maintenance Mode, then choose Exit Maintenance Mode.
5. If you initiated a rolling cluster-wide remediation, vCenter will automatically proceed to the next host in the queue, repeating the evacuation, patching, and validation steps.

vSphere Lifecycle Manager Technical Parameters and Comparison Specs

The choice between legacy Baseline-based management (formerly vSphere Update Manager) and Image-based management (vLCM) dictates how hosts are validated and updated. The following table highlights key operational differences and engineering parameters to consider when planning your lifecycle strategy.

Lifecycle Manager Update Failures and Real-World Remediation

Scenario 1: ESXi Host Fails to Enter Maintenance Mode

During remediation, the task hangs indefinitely at 2% or fails with a timeout error indicating the host cannot enter Maintenance Mode.

• Root Cause: Virtual machines are pinned to the host due to local device connections, such as an active CD-ROM drive mounting an ISO stored on a local datastore, or because of VM-to-Host DRS affinity rules that forbid the virtual machines from running on other nodes.
• Actionable Fix: Edit the settings of the affected virtual machines and disconnect any active CD-ROM or floppy devices. Check the cluster configuration under Configure > VM/Host Rules to determine if any strict "must run on host" affinity rules are blocking migrations. If DRS is set to manual, manually vMotion the remaining virtual machines to another host in the cluster.

Scenario 2: Hardware Compatibility Verification Failure

The vLCM pre-check utility returns a warning or error stating that a local RAID controller or Network Interface Card (NIC) driver is incompatible with the target ESXi version.

• Root Cause: The default ESXi base image contains generic drivers that conflict with specific hardware revisions or do not match the required firmware level of the installed card.
• Actionable Fix: Modify the desired cluster image in vLCM. Under the Vendor Add-On section, select and integrate the specific OEM package provided by your hardware manufacturer (such as Dell or HPE). This add-on injects the correct, certified drivers into the image. Ensure the physical card's firmware is updated to the matching HCL-approved level using the host's out-of-band management controller (iDRAC, iLO) before restarting the update.

Scenario 3: Remediation Fails Due to Insufficient Boot Bank Space

The update process halts with an error pointing to an inability to write the new system image, stating there is not enough free space on the boot device.

• Root Cause: The ESXi host boot device is running on a legacy or constrained flash drive (such as an old USB stick or small SD card) that lacks the capacity for modern ESXi 7.0 or 8.0 system storage layouts, or the scratch partition is incorrectly configured to run on temporary RAM disk space.
• Actionable Fix: Configure a persistent scratch partition on a local or remote SAN datastore to offload system logs and diagnostic core dumps. If the physical boot media is smaller than 32 GB, plan a migration to high-endurance local SSDs, M.2 flash devices, or BOSS cards, as VMware has deprecated low-endurance SD/USB boot media for system installations.

Frequently Asked Questions

Can I mix different ESXi versions inside a single vSphere cluster?

Yes, you can temporarily run mixed ESXi versions within the same DRS and HA cluster during an active upgrade window. However, this state should only be maintained during the transition period; once the vCenter upgrade is complete, all hosts within the cluster should be updated to the same target version to avoid performance mismatches, resource scheduling anomalies, or vMotion compatibility issues.

How do I rollback an ESXi host if an update fails to boot?

If an ESXi host fails to boot after an update, restart the physical server and watch the console during the boot phase. Press Shift + Y when prompted on the loading screen to access the hypervisor boot recovery menu. From there, select the previous ESXi installation bank to roll back the hypervisor to its pre-update version and build state.

What is the difference between staging and remediating in vSphere Lifecycle Manager?

Staging downloads the necessary software packages, patches, and drivers from the vCenter repository to the local storage of the target ESXi hosts while they remain active and operational. Remediating is the subsequent installation step, which requires the host to enter Maintenance Mode, migrate its workloads, apply the staged packages, and restart the physical server.

Why is the vSphere Lifecycle Manager option grayed out on my cluster?

The vLCM image options will be unavailable if your cluster is still configured to use legacy Update Manager baselines. To resolve this, navigate to your cluster, select the Updates tab, and click the option to transition the cluster from baselines to images. Note that once you convert a cluster to use a single declarative image, you cannot revert it back to using traditional baselines.

Optimize Your Virtualization Infrastructure

For organizations looking to secure their bare-metal hypervisor fleet and implement automated configuration management, establishing a robust lifecycle strategy is essential. Reach out to our enterprise systems integration team today to schedule an architecture review and transition your legacy vSphere environments to modern, declarative Lifecycle Manager workflows.