Preparing VMs for import

x86 The most common CPU architecture. x86 CPUs support Windows and Linux VMs in Skytap. VM files must meet the import requirements listed below.

To prepare Power A CPU architecture that supports IBM i, AIX, and Linux (on Power) in Skytap. VMs for import, see Importing Power VMs into Skytap.


Virtual hardware limits

The virtual hardware configuration of each VM to be imported—CPU cores, RAM, total storage, and the number of disks—must fall within the virtual hardware capabilities of the Skytap region where it will be imported.

For detailed virtual hardware limits by region, see Skytap service limits.

VM file format

Skytap supports OVA files, OVF packages, and VMX files that were created in a VMware hypervisor (VMware Server, VMware Workstation, VMware ESX, etc.). For single VM imports, we recommend OVF format.

If you have virtual machines created in a non-VMware hypervisor, you must convert them before you can import them. For instructions, see Converting non-VMware-based VMs for import.

An import job can contain multiple OVF packages, OVA files, or VMX files. Additionally, you can mix and match file types in an import job. During the import process, Skytap combines the VMs in the import job into a single environment.

Supported file type Description
OVF v1.0 or 1.1 with VMDK disks
An OVF file must be imported with its VMDK disk images.


  • An OVF package can contain multiple disk image files for a VM that is configured to split a virtual hard disk into multiple files. For more details about OVF packages, see the OVF Tool User's Guide.
  • Manually created OVF files that contain multiple VMs are more likely to fail.
Recommended for bulk imports
An OVA file is a compressed file package that contains VM configuration information and all VM disks. An OVA file can contain multiple VMs (such as a multi-VM environment).
OVA files retain the most information while taking slightly less time to upload.
VMX with VMDK disks A VMX file must be imported with its VMDK disk images.

A VMX package can contain multiple disk image files for a VM that is configured to split a virtual hard disk into multiple files.


  • Don't use the following characters in your file names:  '   "   \   ` .
  • During the import process, Skytap removes information included in the ExtraConfig element of each VM file.
Notes about VMDK disk image types
  • Skytap doesn’t support 2gbsparse or monosparse VMDK disks. Use thin or thick-provisioned disks instead. For instructions about converting a disk, see the VMware KB for cloning or converting virtual disks.
  • During import, Skytap expands each thin-provisioned disk to its maximum size. For example, a thin-provisioned disk with 2 GB of usage but up to 10 GB of capacity will be expanded to 10 GB.
  • For more information about VMDK disks, see the VMware article about ESXi-supported disks.

Hardware version

Each VM must use VMware hardware version 6, 7, 8, 9, 10, or 11.

Hardware version 11 is recommended for VMs. For more information, see Hardware version compatibility in Skytap.

Virtual hard disk type

When you build VMs, Skytap recommends that you choose the SCSI hard disk type.

Hard disk type Notes
A SCSI hard disk suspends and resumes more quickly than an IDE hard disk.
Additionally, a SCSI hard disk can be extended after import.
IDE An IDE hard disk can’t be extended after it’s imported.
SATA Not supported.

Disks attached to a SATA controller are excluded during import. This can result in a VM without storage.

Power state

Each VM in the import job must be powered off.

VM optimization

Before you export a VM, make sure it uses settings that work best when you import it into Skytap.

  • Remove snapshots or linked copies from VM files. Use VMware Workstation or the free VMware Converter tool to remove snapshots, or import a copy of the VM (copying a VM merges all snapshots into its VMDK files).
  • Leave one IDE interface available for Skytap to add a CD/DVD drive (to load ISOs).

    For more information, see Using ISO files.

  • If you don’t have manual networking defined for your VMs, configure the VMs to use DHCP networking. Skytap creates automatic networking for your environment.

File compression

Compression can slightly reduce the amount of time it takes to upload VMs, especially if you have multiple VMs or large VMs with lots of empty disk space.

Compression format Description
OVA files
When VMs as OVA files, they’re already compressed.
You can use the VMware OVF Converter Tool to compress a VMX-based VM into a single OVA file.
7z files

If you can't create OVA files, you can compress the OVF/VMDK or VMX/VMDK files into a 7z file, using the following settings:

  • Archive format: 7z
  • Compression level: Normal
  • Compression method: LZMA or LZMA2 (recommended)
7z Utilities
Zip files Not supported

VM size

The combined, uncompressed file size of the entire import job (regardless of the number of files in the job) must be less than 4 TB.

If you have a vApp larger than 4 TB, split the VM import into multiple import jobs.

MAC address restrictions

MAC addresses for all VM network adapters must meet the following requirements:

  • MAC addresses must begin with the hexadecimal digits 00:50:56.
  • The maximum value for a MAC address is 00:50:56:3F:FF:FF.
  • The valid MAC address range is 00:50:56:00:00:00 to 00:50:56:3F:FF:FF.