VMware ESXi and vSphere Cluster Management

Add an Existing Virtual Hard Disk to a VMware Player Virtual Machine

Learn how to attach an existing VMDK virtual disk to a VMware Player virtual machine, choose a compatible controller, and troubleshoot common disk problems.

A VMware virtual machine is a software-defined computer with configurable virtual hardware. Its virtual hard disk is a file on the host computer that the guest operating system uses as storage. VMware virtual disks commonly use the VMDK format, identified by the .vmdk extension.

Instead of creating a new empty disk, you can attach an existing virtual disk to a virtual machine. This is useful when restoring a detached disk, reusing a data disk, or connecting a disk supplied with another virtual machine.

Prerequisites and safety checks

  • Power off the target virtual machine before changing its virtual hardware. Do not change disk attachments while the machine is running.
  • Make sure the existing virtual disk file is accessible from the host computer.
  • Confirm that another powered-on virtual machine is not actively using the disk.
  • Make a backup or a complete copy before attaching a disk containing important data.
  • Verify that your host user account can read the disk location. Write access is also required when VMware must update, lock, or otherwise modify files in that location.
  • Identify whether the disk is independent, part of a snapshot chain, or associated with another virtual machine configuration.

Attaching a writable VMDK to multiple running virtual machines can cause conflicting writes and filesystem corruption. Use one active writer unless a storage arrangement explicitly supports shared-disk access.

Open the target virtual machine settings

  1. Select the intended virtual machine in the VMware Player library.
  2. Make sure it is powered off.
  3. Open the virtual machine management menu.
  4. Choose Player > Manage > Virtual Machine Settings.

The settings dialog controls the virtual machine's virtual hardware, including memory, network adapters, disks, and disk controllers.

Start the New Hardware wizard

  1. Open the Hardware tab.
  2. Click Add to start the New Hardware wizard.
  3. Select Hard Disk as the device type, then continue.

Adding a hard disk adds a virtual storage device and its connection to a virtual controller. It does not automatically create an operating-system-visible drive letter, mount point, or filesystem.

Choose the virtual disk interface type

The wizard may ask which disk or controller type to use. Common choices are IDE, SCSI, SATA, and NVMe. Availability depends on the VMware Player version, the virtual machine hardware compatibility level, and the guest operating system.

When possible, match the controller type expected by the existing disk and supported by the guest. A guest operating system may fail to access a disk if it lacks the required controller driver.

Controller type | Compatibility consideration | Typical use case

IDE | Broad legacy compatibility, but fewer modern features | Older guest operating systems or legacy virtual machines

SCSI | Common in VMware configurations; guest drivers may be required | General-purpose disks and many server-style guests

SATA | Common desktop-compatible interface | Modern desktop guests and broadly compatible configurations

NVMe | Requires suitable VMware hardware compatibility and guest support | Modern guests that support virtual NVMe storage

Do not change a controller type casually when reusing a system disk. The guest may depend on the original controller driver, especially when the disk contains an operating system.

Select Use an existing virtual disk

The wizard normally presents choices for how to provide storage:

Wizard choice | When to use it | Result

Create a new virtual disk | You need a blank disk for a new guest, application, or data volume | VMware creates a new empty virtual disk file

Use an existing virtual disk | You already have a VMDK that should be reused or restored | VMware attaches the selected existing virtual disk

Use a physical disk | A physical host disk must be exposed directly to the guest and the arrangement is intentionally configured | The guest accesses physical storage rather than a normal file-based VMDK

Select Use an existing virtual disk. This is different from creating a blank virtual disk: the existing file may already contain an operating system, partitions, applications, or user data.

Locate and select the VMDK file

  1. Click the browse control in the wizard.
  2. Navigate to the folder containing the existing virtual disk.
  3. Select the main virtual disk descriptor file, typically ending in .vmdk.
  4. Complete the wizard and save the virtual machine hardware changes.
  5. Reopen the hardware settings if necessary and verify that the disk appears in the hardware list.

A virtual disk descriptor is a VMDK metadata file that describes the disk and may reference one or more backing files called disk extents. A split virtual disk stores its data in several extent files instead of one large file.

If the disk is split, select the descriptor VMDK rather than an individual numbered extent. Keep the descriptor and every referenced extent in the expected folder structure.

Component | Typical naming pattern | Purpose | Must be kept together

VMDK descriptor file | A small file such as server.vmdk | Describes disk geometry, format, and referenced backing files | Yes, with all referenced files

Single-file VMDK | One disk file such as data.vmdk | Stores descriptor information and disk data in one file | The file must remain accessible

Split-disk extent files | Files with numbered names such as data-s001.vmdk | Store portions of the virtual disk data | Yes, with the descriptor and other extents

Snapshot-related disk files | Names often containing snapshot or delta indicators | Store changes made after a snapshot | Yes, with the complete snapshot chain

Moving a VMDK requires moving all associated files. Preserve relative locations referenced by the descriptor. A missing extent or snapshot-dependent file can prevent VMware from opening the disk.

Boot the guest and verify the disk

  1. Save the hardware changes and start the virtual machine.
  2. Wait for the guest operating system to finish booting.
  3. Use the guest's disk-management tools to confirm that the added storage device is detected.
  4. For a data disk, initialize it, mount its filesystem, or assign a drive letter only when appropriate.

Detection is not the same as mounting. A guest may see the device but leave it offline, without a drive letter, or without a mounted filesystem. Do not initialize or format a disk that contains data unless you have confirmed that this operation is safe.

If the VMDK contains an operating system, attaching it as a secondary disk does not necessarily make it bootable. Booting from it may require changing the boot order, connecting it to the expected controller, and ensuring that the guest has drivers and boot configuration compatible with the target virtual machine.

Practical examples

Attach a previously removed data disk

  1. Power off the target virtual machine.
  2. Open its virtual machine settings.
  3. Use Hardware > Add > Hard Disk.
  4. Choose a controller type supported by the guest and expected by the disk.
  5. Select Use an existing virtual disk.
  6. Browse to the VMDK descriptor and finish.
  7. Boot the guest and confirm that the data volume is available.

Attach a split VMDK

  1. Locate the small descriptor VMDK and all accompanying extent files.
  2. Keep the files in the same expected folder structure.
  3. Select the descriptor file in VMware Player.
  4. Do not select a numbered extent as a substitute for the descriptor when both are present.

Use a disk from another virtual machine as a secondary disk

  1. Power off the source virtual machine.
  2. Ensure the source machine will not use the disk while the target is running.
  3. Attach the VMDK to the target machine.
  4. Use it as a secondary data disk unless a deliberate boot migration is planned.

Troubleshooting

The VMDK cannot be selected or opened

Likely causes include a missing descriptor, missing extent files, selecting an extent instead of the descriptor, insufficient host permissions, or a lock held by another virtual machine or process.

  • Verify that every file belonging to the disk is present.
  • Select the main descriptor VMDK for a split disk.
  • Check that the host account can access the folder and files.
  • Power off other virtual machines that may be using the disk and check for other processes holding it open.

The guest starts but cannot see the added disk

Confirm that the hard disk appears in VMware Player's hardware settings and that the changes were saved. If it does, the controller type may be unsupported by the guest, or the guest may have detected the disk without mounting or assigning it.

  • Rescan storage using the guest operating system's disk-management tools.
  • Try a guest-compatible controller type when changing it is safe.
  • Initialize, mount, or assign the disk only if it is a new or intentionally blank disk.

The guest cannot boot after attaching an old system disk

The disk may be connected as a secondary device rather than the startup disk. The guest may also lack drivers for the selected controller, or its boot configuration may not match the target virtual machine.

  • Treat the disk as a data disk unless boot migration is specifically intended.
  • Review boot order, controller compatibility, and guest driver requirements.
  • Keep a backup before attempting repairs to boot configuration or filesystem structures.

Disk corruption or conflicting changes occur

This commonly results from attaching the same writable VMDK to multiple active virtual machines, moving only part of a snapshot chain, or renaming files without preserving descriptor references.

  • Use one active writer unless a properly configured shared-storage solution is in use.
  • Restore the complete disk and snapshot file set from backup.
  • Avoid renaming or separating disk components unless you understand the references between them.

Key points

  • Use Use an existing virtual disk when you want to attach an existing VMDK rather than create a blank disk.
  • Select the descriptor VMDK for split disks and keep all extent files together.
  • Choose a controller supported by both VMware Player and the guest operating system.
  • Power off virtual machines before changing virtual hardware.
  • Do not allow multiple running virtual machines to write to the same ordinary VMDK.
  • Attaching an operating-system disk does not automatically make it the boot disk.