With VMware’s licensing and ownership changes under Broadcom, many organizations are reevaluating their virtualization platforms. In 2025, one of the fastest-growing trends is the migration from VMware ESXi to Proxmox VE 9, an open-source and enterprise-grade alternative built on KVM and LXC.

Migrating a few VMs is simple — but migrating hundreds or thousands of VMs efficiently requires planning, automation, and the right tools. This blog post explains how to perform large-scale VM migration from VMware ESXi 8.x or 7.x to Proxmox VE 9 with minimal downtime and maximum consistency.

Why Organizations Are Migrating to Proxmox VE 9

• No licensing costs – fully open source with enterprise support options

• Unified virtualization & container management – KVM, LXC, ZFS, and Ceph in one platform

• Automation-friendly – robust API, CLI, and Ansible/Terraform integration

• Enterprise-grade stability – high availability, clustering, and live migration support

These benefits make Proxmox VE 9 a powerful replacement for VMware ESXi in both enterprise and SMB environments.

Migration Overview

For large environments, the best method is the virt-v2v-based migration, supported by automation scripts for batch processing.

Step 1: Assessment & Planning

Before you move anything, take inventory and plan carefully.

1.1 Inventory Your VMs

Export a complete list of your VMware VMs using PowerCLI:

1.2 Check Compatibility

• Ensure all VMs use SCSI/SATA controllers and BIOS/UEFI compatible boot modes.

• Remove VMware Tools before export.

• Record OS versions for driver preparation (especially Windows).

1.3 Define Migration Strategy

• Production VMs: schedule during maintenance windows

• Non-critical VMs: batch migrate during testing

Step 2: Prepare Proxmox VE 9 Cluster

1. Install Proxmox VE 9 on target nodes with all security updates.

2. Configure networking, storage, and Proxmox Backup Server.

3. If using shared storage, set up Ceph, NFS, or iSCSI.

4. Install conversion tools:

   apt install qemu-utils libguestfs-tools virt-v2v

Step 3: Conversion and Import

Using virt-v2v (Recommended Method)

1. Export VM from ESXi

   ovftool vi://user@esxi-host/vm-name /tmp/vm-export/


2. Convert VM to Proxmox Format

   virt-v2v -i vmx /tmp/vm-export/vm.vmx -o local -os /var/lib/vz/images/


3. Import into Proxmox

   qm create 101 --name myvm --memory 4096 --cores 2 --net0 virtio,bridge=vmbr0
qm importdisk 101 /var/lib/vz/images/myvm.qcow2 local-lvm
qm set 101 --scsihw virtio-scsi-pci --scsi0 local-lvm:vm-101-disk-0 --boot order=scsi0


4. Install virtio Drivers

   • For Windows: mount virtio-win.iso before booting.

   • For Linux: most modern kernels include virtio by default.

Step 4: Automate for Large-Scale Migration

When migrating dozens or hundreds of VMs, scripting is key.

Here’s a simple automation loop:

You can enhance this with:

• Logging for tracking progress

• Error handling

• Integration with Proxmox API (pvesh create /nodes/.../qemu)

Step 5: Validation & Testing

Before decommissioning VMware:

1. Boot each migrated VM in Proxmox test cluster

2. Validate:

   • Network interfaces

   • Disk performance

   • Application services

3. Fix any missing drivers or IP mismatches

4. Once stable, power off VMware VMs

Common Migration Issues & Fixes

Bonus: Advanced Proxmox Migration Setup

For enterprise setups:

• Use Proxmox Backup Server (PBS) for incremental backups & restores

• Deploy Ceph storage for high availability

• Automate deployments with Ansible or Terraform

These tools streamline migration management and future scaling.

Summary

Migrating from VMware ESXi to Proxmox VE 9 in 2025 is a strategic move for organizations seeking open-source freedom, cost control, and infrastructure flexibility.

Key takeaways:

• Use virt-v2v for efficient and automated conversions

• Plan, script, and validate at every step

• Integrate PBS or Ceph for high performance

• Test thoroughly before decommissioning VMware

With careful planning and the right automation, Proxmox VE 9 can become your reliable, cost-effective foundation for the next generation of virtualization.