ESXi vLCM Upgrade Fails Cannot Create Ramdisk of Size 397MB

Products

• VMware vSphere ESXi

Issue/Introduction

During a vSphere Lifecycle Manager (vLCM) upgrade of an ESXi host, the pre-check or remediation task fails with the following errors:

Hardware configuration of host is incompatible. Check scan results for details

If you look in the details section of the failed task you will see additional information. 

Cannot create a ramdisk of size 397MB to store the upgrade image. Check if the host has sufficient memory.

This occurs even when the host hardware matches successfully upgraded hosts, total physical memory is adequate, and the scratch partition is correctly configured to a persistent datastore.

Environment

VMware vSphere ESXi 7.0 u3

Cause

Extended host uptime or third-party management agents cause physical memory (RAM) fragmentation. This fragmentation prevents the hypervisor kernel from allocating the strictly contiguous 397MB memory block required to dynamically provision the staging ramdisk for the upgrade payload.

Resolution

 

1. Verify you have evacuated all virtual machines from the affected ESXi host.

2. Place the host into Maintenance Mode.

3. Reboot the ESXi host to clear volatile storage and defragment the physical memory.

4. Wait for the host to reconnect to the vCenter Server inventory.

5. Re-initiate the vLCM remediation task immediately to stage the payload before memory fragments again.

 

Additional Information

VMware Cloud Foundation: ESXi Upgrade bundle validation check or upgrade fails

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