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Version: 0.x (legacy)

VMware migration guide

The screenshot and its detail below are from a real registered source; the step-by-step wording around them is still being verified end to end.

Ballast can import a VM's disks directly from VMware-accessible storage and register it as a Hyper-V VM, without a separate conversion tool run by hand.

Before you start​

  • Confirm the guest OS is one Hyper-V supports as a generation 1 or 2 VM.
  • Linux guests: a VM migrated from VMware commonly boots to what looks like a missing disk. This is usually the initramfs/dracut image built for the old hypervisor's storage drivers, not an actual data loss — install hyperv-daemons-equivalent drivers into the image (or rebuild the initramfs) before or immediately after migration. See Troubleshooting.
  • Ballast has no in-guest channel into a Linux guest the way it does for a Windows guest with the Hyper-V integration services — plan any in-guest driver work as a manual step.

1. Register a source and scan it​

Register a VMware source (a vCenter or a standalone ESXi host); Ballast reads what it holds and what each VM arrives as before anything is copied:

Ballast console VMware source showing a connected ESXi host and three discovered VMs, one ready, one ready for warm migration, one blocked with a specific reason

Each discovered VM is filterable by whether it is ready, ready for a warm migration, cold-only, blocked, or already migrated — and blocked VMs say exactly why. A real example: a VM whose disk is a raw device mapping is blocked with "Hard disk 2 is a raw device mapping", and the console explains what that means and what to do about it rather than leaving the operator to work it out:

A raw device mapping points at a LUN rather than holding data, so there is nothing to copy. Present that LUN to Hyper-V instead and attach it after the migration.

2. Import​

Choose a scanned VM and import it. This registers a new Hyper-V VM from the existing virtual disks. The source's VMDK is never attached in place — Ballast streams it (via a VMware snapshot export lease) directly into a newly created VHDX on the destination host or CSV, converting as it goes. Because the stream only carries grains where the source disk actually has data, a thin disk crosses the wire at roughly what it occupies rather than what it claims.

3. Verify and reconfigure networking​

An imported VM's network adapters do not carry over VMware's vSwitch/port group model — Hyper-V has no dvSwitch or dvport equivalent. Reattach the guest's vNICs to the correct vSwitch and, if used, VLAN as a normal desired-state edit after import.

4. Power on and confirm​

Start the VM and confirm the guest boots and its network is reachable. For a warm migration of a VM that must stay running until cutover, note that a running guest holds a lock on its own base disk — see Troubleshooting for what that means for timing.

What is not supported yet​

  • Bulk/batch migration of many VMs in one action.
  • Live (zero-downtime) migration directly from a running VMware host.

Both are tracked on the roadmap; this page will be updated when either ships.