Migrating Windows virtual machines from VMware to STACKIT

A SQL Server VM with three disks

Left: the three disks of win-sql01 from the vDisk sheet. Right: the blocks of compute.tf for that server, without the review comments above each block.

VM,Disk,Capacity MiB,Raw,Disk Mode,Sharing mode,Thin,Controller,Shared Bus,Disk Path,VM UUID
win-sql01,Hard disk 1,102400,False,persistent,sharingNone,False,SCSI controller 0,noSharing,[ds-prod-01] win-sql01/win-sql01_0.vmdk,4202-vm12-0004
win-sql01,Hard disk 2,512000,False,persistent,sharingNone,False,SCSI controller 1,noSharing,[ds-prod-01] win-sql01/win-sql01_1.vmdk,4202-vm12-0004
win-sql01,Hard disk 3,204800,False,persistent,sharingNone,False,SCSI controller 2,noSharing,[ds-prod-01] win-sql01/win-sql01_2.vmdk,4202-vm12-0004

resource "stackit_network_interface" "vm_win_sql01_nic1" {
  project_id = var.project_id
  network_id = stackit_network.network_PG_Win_Data.network_id
  ipv4       = "10.30.20.31"
}

resource "stackit_server" "vm_win_sql01" {
  project_id        = var.project_id
  name              = "win-sql01"
  machine_type      = var.vm_win_sql01_machine_type
  availability_zone = var.availability_zone
  boot_volume = {
    source_type = "image"
    source_id   = var.vm_win_sql01_image_id
    size        = 100
  }
  network_interfaces = [stackit_network_interface.vm_win_sql01_nic1.network_interface_id]
}

resource "stackit_volume" "vm_win_sql01_disk2" {
  project_id        = var.project_id
  name              = "win-sql01-disk2"
  availability_zone = var.availability_zone
  size              = 500
  performance_class = var.vmware_volume_performance_class
}

resource "stackit_server_volume_attach" "vm_win_sql01_disk2" {
  project_id = var.project_id
  server_id  = stackit_server.vm_win_sql01.server_id
  volume_id  = stackit_volume.vm_win_sql01_disk2.volume_id
}

resource "stackit_volume" "vm_win_sql01_disk3" {
  project_id        = var.project_id
  name              = "win-sql01-disk3"
  availability_zone = var.availability_zone
  size              = 200
  performance_class = var.vmware_volume_performance_class
}

resource "stackit_server_volume_attach" "vm_win_sql01_disk3" {
  project_id = var.project_id
  server_id  = stackit_server.vm_win_sql01.server_id
  volume_id  = stackit_volume.vm_win_sql01_disk3.volume_id
}

• Boot disk

  Hard disk 1, 102400 MiB, becomes a boot volume of 100 GiB. The server starts from an image you supply through a variable.

• Data disks

  Hard disk 2 with 512000 MiB and hard disk 3 with 204800 MiB become volumes of 500 and 200 GiB, each attached by its own attach block. Their contents are copied after the volumes exist.

• The image is not in the draft

  StackToIT does not convert or upload disks. The image ID is an input, and the next section shows how it is declared.

What the draft asks you for

Left: the vInfo row of win-sql01. Right: the two variables its server reads, from variables.tf.

VM,Powerstate,Template,CPUs,Memory,NICs,Disks,Provisioned MiB,In use MiB,Primary IP Address,DNS Name,Datacenter,Cluster,Host,Folder,Firmware,HW version,Path,Annotation,OS according to the configuration file,OS according to the VMware Tools,VM UUID
win-sql01,poweredOn,False,8,65536,1,3,819200,573440,10.30.20.31,win-sql01.corp.example,DC-Munich,CL-Prod,esx11,prod,bios,vmx-19,[ds-prod-01] win-sql01/win-sql01.vmx,SQL Server 2019 Standard,Microsoft Windows Server 2019 (64-bit),Microsoft Windows Server 2019 Standard,4202-vm12-0004

variable "vm_win_sql01_image_id" {
  type        = string
  description = "STACKIT image converted from the boot disk of VM win-sql01 (qcow2 or raw)."
}

variable "vm_win_sql01_machine_type" {
  type        = string
  description = "STACKIT machine type replacing VM win-sql01 (source 8 vCPU / 64 GiB). See https://docs.stackit.cloud/products/compute-engine/server/basics/machine-types/"
}

• Size is stated, not chosen

  The source has 8 CPUs and 65536 MiB. The machine type variable repeats that as 8 vCPU and 64 GiB and links the STACKIT machine types, so you choose a catalogue name.

• Windows narrows the choice

  The machine type page has a Windows Server compatible column for each family. Check it before you pick.

• Image from the boot disk

  The image variable stands for the boot disk after conversion to qcow2 or raw.

The Windows template

Left: the vInfo row of tpl-win2022. Right: the line of the README in terraform/ that lists it under Left for the architect.

VM,Powerstate,Template,CPUs,Memory,NICs,Disks,Provisioned MiB,In use MiB,Primary IP Address,DNS Name,Datacenter,Cluster,Host,Folder,Firmware,HW version,Path,Annotation,OS according to the configuration file,OS according to the VMware Tools,VM UUID
tpl-win2022,poweredOff,True,2,4096,1,1,61440,30720,,,DC-Munich,CL-Prod,esx11,prod,efi,vmx-19,[ds-prod-01] tpl-win2022/tpl-win2022.vmx,"Golden image, sysprepped",Microsoft Windows Server 2022 (64-bit),,4202-vm12-0007

| Source | Class | Why |
|---|---|---|
| `vm.tpl-win2022` | REPLATFORM / MEDIUM | VM template: convert the VMDK to qcow2/raw and upload it with stackit_image, or rebuild it from a STACKIT public image. |

• No image block is written

  A template is classified REPLATFORM. The run writes no image for it: you convert the disk and upload it, or rebuild it from a STACKIT public image.

• Firmware stays open

  The template boots with EFI. The run leaves BIOS or EFI open and notes that it is a property of the uploaded image, which you create.

What the run says about each Windows VM

The statements in the middle column are the messages of assessment.json and engineering/architect-report.md of the run, shortened. The run reads the guest OS from the configuration file; the OS reported by VMware Tools is left to a person to compare.

The migration in order

1. 01

   Export all sheets and read the guest OS twice

   Include vSnapshot and vMemory in the RVTools export so snapshots and reservations are known. Compare the configuration-file OS with the one VMware Tools reports: the end-of-support check reads only the first.

2. 02

   Decide the licence route per VM

   As of November 2026, the STACKIT operating system images page lists Windows Server 2025, 2022, 2019 and 2016 Standard images with the licence included, or you bring your own image and licences. Section Licence decisions lists what each route means.

3. 03

   Choose machine types

   Start from the exported CPUs and memory, then keep to the families marked compatible with Windows Server on the machine type page.

4. 04

   Prepare the guest

   Consolidate snapshots. STACKIT's own Windows example installs the VirtIO drivers NetKVM, Viostor and Vioscsi, installs Cloudbase-Init and runs Sysprep before conversion. That example starts from Hyper-V, so treat it as a model and test the same steps on a copy of your VMware guest.

5. 05

   Convert and upload

   Convert the disk with qemu-img to qcow2 or raw, create the image through the CLI or API, upload the file and wait until the image state is AVAILABLE. The custom image page states a maximum image size of 70 GB; check your converted disk against it.

6. 06

   Create volume, server and data volumes

   Apply the draft once networks, image ID and machine type are filled. The server starts from the image; data volumes follow.

7. 07

   Join the domain and verify

   The STACKIT domain join command needs DNS servers that resolve your domain and a domain controller reachable on the local network. Check Device Manager for missing drivers.

8. 08

   Cut over and retire

   Move traffic when the checks pass. Keep the source VM stopped but intact until the owner signs off. This is general practice, not a run output.

Licence decisions

• Licence included

  With a STACKIT Windows Server Standard image the operating system licence is included, Client Access Licences are not required, and Remote Desktop subscriber licences are not provided or charged; you bring those.

• Your own image and licences

  For a customer-provided image STACKIT provides no Windows licence and the customer is responsible for proper licensing. The guide names this route FVB and attaches conditions such as subscription licences or active Software Assurance; server licences without it are listed as not eligible.

• Custom image and licensing agent

  The images page says Windows licences cannot be migrated and that a custom image needs contact with STACKIT to install the licensing agent, while the licensing guide says no scanning agent is installed on customer-provided images. Ask STACKIT which applies to you.

• Versions STACKIT supports

  STACKIT provides only Windows Server versions that Microsoft still supports; the images page lists Microsoft's end-of-support date per version, so recheck it when you plan. A 2012 R2 guest therefore needs an upgrade or a custom image at your own risk.

• SQL Server and other products

  The licensing guide treats server applications and SQL Server as allowed when properly licensed. Read its per-product list for your estate.

Questions Windows teams ask

Sources

• STACKIT documentation: Windows Server licensing guide
• STACKIT documentation: Windows Server operating system images
• STACKIT documentation: machine types
• STACKIT documentation: use custom images with the IaaS API
• STACKIT professional services: Windows BYOL migration example
• STACKIT documentation: join a Windows Server to a domain