What Is a Virtual Disk in VMware Player?

Learn how VMware Player virtual disks work, including VMDK files, guest capacity, host storage, allocation types, portability, and safe disk management.

A virtual disk is software-defined storage that VMware Player presents to a virtual machine as a hard drive. The host operating system sees one or more files in a folder, while the guest operating system sees a normal usable disk.

The guest can partition, format, and use this disk much like a physical drive. It can contain the guest operating system, installed applications, documents, databases, and other guest data.

Virtual Disk Concepts: Host View and Guest View

Concept	Host-side view	Guest-side view	Why it matters
Virtual disk	One or more files in the host filesystem	A disk drive connected to the virtual machine	The two systems report storage differently
Capacity	Maximum size the disk file can reach	Disk size reported to the guest	Guest capacity is not the same as current host usage
Data	Encoded in the virtual disk files	Files, partitions, applications, and operating-system data	Protecting the disk files protects important guest data
Attachment	A configuration reference to the disk file	A disk available through virtual hardware	Moving or detaching the file can break the connection

What a Virtual Disk Stores

A virtual machine is a software-based computer with virtual hardware such as processors, memory, network adapters, and disks. The virtual disk is one major component of that computer, but it is not the same as the virtual machine's configuration files.

The virtual disk stores guest data, including the operating system, applications, user documents, databases, and settings.
Virtual machine configuration files describe hardware and settings such as allocated memory, virtual processors, device attachments, and disk paths.
A complete virtual machine normally needs both its configuration files and all related virtual disk files.

For an overview of the file types that can make up a virtual machine, see Virtual Machine Files.

Understanding VMDK Files

VMware commonly uses the .vmdk extension for virtual disks. VMDK is VMware's virtual disk file format.

One logical disk shown inside the guest can correspond to a single VMDK file or to multiple related files on the host. The exact arrangement depends on how the disk was created and managed. Do not assume that one visible file is the entire disk.

Two sizes are especially important:

Virtual disk capacity: the maximum size the disk reports or can grow to from the guest's perspective.
Host filesystem usage: the amount of physical space currently consumed by the disk files on the host.

For example, a 100 GB growable virtual disk might initially use about 15 GB on the host. As the guest writes more data, the host files can grow, but the virtual disk should not exceed its configured 100 GB capacity. The guest may also have unused space inside its partitions, so guest free space and host free space are separate measurements.

Creating a Virtual Disk During VM Setup

The new virtual machine workflow normally creates an initial virtual disk. During setup, you commonly choose:

the virtual disk's maximum capacity;
the folder or drive where the virtual machine files will be stored; and
whether storage uses growable or preallocated allocation, when that option is available.

The initial disk is commonly the guest's boot disk. The guest operating-system installer can partition and format it, then place the operating system on it. A disk configured as 60 GB therefore appears to the installer as a 60 GB drive, even if a growable disk initially consumes much less physical space on the host.

For the complete creation process, see Create a Virtual Machine.

Growable Versus Preallocated Storage

A disk's allocation method determines how its host storage is reserved. It does not change the disk's logical role as a drive presented to the guest.

Characteristic	Growable allocation	Preallocated allocation
Initial host-space use	Usually smaller than the configured maximum	Capacity is reserved at creation time
Growth	Host files expand as the guest writes data	Space is already reserved
Creation time	Often quicker	Can take longer because storage is reserved
Capacity planning	Requires monitoring future host free space	Requires enough host space immediately
Potential benefit	Uses only the space currently needed	Provides predictable reservation and may offer performance advantages in some workloads
Important limitation	It can still consume the full configured capacity on the host	Reserved space is unavailable for other host uses

A 60 GB growable disk does not guarantee that the host can provide 60 GB later. The host must have enough free space as the guest installs software and saves files. A preallocated 80 GB disk reserves that space at creation time, which can be useful when fast local storage is available and predictable capacity is more important than minimizing initial usage.

Managing Disks Attached to a Virtual Machine

Disk attachments define which virtual disk files are connected to the virtual machine's virtual hardware. Open the VM's hardware settings to inspect or manage its virtual hard disks. The exact controls depend on the VMware Player version and the VM's current state.

Adding another virtual disk

You can add a second disk for project files, databases, application data, or a separate guest volume. Keeping the operating system on the original disk and data on a second disk can make data management and backups easier.

After VMware Player attaches the new disk, the guest may not use it immediately. The guest operating system might require you to initialize, partition, and format the disk with its own disk-management tools.

See Add a New Virtual Hard Disk for a disk-creation workflow, or Add an Existing Virtual Hard Disk when using a disk file that already exists.

Removing or detaching a disk

Removing a disk from the VM's hardware configuration and deleting its underlying files are separate actions:

Detach or remove from hardware: the VM no longer connects to the disk, but the VMDK files may remain on the host.
Delete the files: the host storage is reclaimed, but the disk's guest data is destroyed unless another copy or backup exists.

Before removing a disk, confirm that it is not the boot disk, verify which guest data it contains, and make a backup. See Remove a Virtual Hard Disk for the related operation.

Other adjustable settings

Depending on VMware Player capabilities, you may be able to inspect or change a disk's capacity, location, and allocation method. Power off the VM before changing disk attachments or performing storage operations unless the specific operation explicitly supports another state.

Increasing a disk's configured capacity is not automatically the same as increasing a guest partition. After expanding a disk, the guest may still need its own partition and filesystem tools to use the additional space. Reducing a disk is more restrictive and can cause data loss if the guest data is not reduced first.

More disk-specific configuration guidance is available in Configure a Virtual Hard Disk and Expand a Virtual Hard Disk.

Portability and Storage Location

Virtual disks are portable because their contents are stored in host files. You can move a virtual machine or its storage to another folder, drive, or compatible computer, provided that you preserve the required files and reconnect the configuration to the new location when necessary.

Shut down the guest operating system normally.
Confirm that VMware Player is no longer running the VM and that it is not suspended or being used by another process.
Move or copy the complete VM folder, including the configuration files and all related VMDK files.
Open the VM from its new location, or update the disk-file path if the configuration still refers to the old location.
Confirm that the guest can see its expected disks before deleting the original copy.

Move disk files only while the VM is fully powered off and not in use. A suspended or running VM can still have pending writes, making a file copy inconsistent. For a broader relocation procedure, see Move a Virtual Machine.

Safe Handling Rules

Do not manually rename, edit, or delete VMDK-related files unless you understand the VM's dependencies and configuration references.
Do not copy a virtual disk while the guest is writing to it. Use a clean shutdown or a supported backup method.
Back up the VM before resizing, relocating, removing, or converting disk storage.
Keep related disk files together unless you know how the disk's descriptor and data files are connected.
Track host free space, not only the disk capacity shown by the guest.
Remember that a configured maximum size is a limit, not a guarantee that the host has that much available storage.

Common Problems and Fixes

The host drive runs out of space

A growable disk expanded as the guest wrote data and exhausted host storage. Free or add host storage, or move the powered-off VM to a larger drive. Monitor host free space as well as guest-reported capacity.

The VM cannot find its disk after moving files

The configuration may still reference the old VMDK path, or only part of the related file set may have been moved. Restore the complete VM file set or reconnect the correct disk from its new location while the VM is powered off.

A copied VM contains missing or unusable data

The files may have been copied while the VM was running or suspended. Make a clean shutdown, then recopy the complete VM from that consistent state or restore from a backup.

Guest data disappeared after a disk was removed

Determine whether the disk was merely detached or whether its VMDK files were deleted. If the files still exist, reattach the correct disk if appropriate. If they were deleted, restore the data from a backup.

The guest cannot use the full size of an added disk

Attaching a disk makes it available to the guest, but does not necessarily initialize, partition, or format it. Use the guest operating system's disk-management tools to prepare the new drive.

Practical Examples

Creating a first Linux VM

You create a Linux VM with a 60 GB virtual disk and choose growable allocation. The installer sees a 60 GB drive, while the host initially uses only the storage needed for the disk's current contents.

Adding separate data storage

You leave the guest operating system on its original disk and attach a second virtual disk for project files. The guest then prepares that disk as a separate volume.

Watching a growable disk expand

A 100 GB growable disk initially occupies 15 GB on the host. Installing applications and saving files causes host usage to increase, but the configured virtual capacity remains capped at 100 GB.

Choosing preallocation

You have sufficient fast local storage and create an 80 GB preallocated disk. The host reserves the space immediately, reducing uncertainty about whether future writes will fit, but that space cannot be used for other host files.

Moving a VM to another drive

After a clean shutdown, you copy the complete VM folder, including configuration and VMDK files, to another drive. You open the VM from the new location and verify its disks before removing the old copy.

Removing a secondary disk safely

You confirm that the secondary disk is not the boot disk, back up its data, and choose whether to disconnect it from the VM while retaining its files or delete the storage files as a separate, irreversible step.

Exam-Relevant Summary

A virtual disk is host-side storage presented to a guest as a disk drive.
The guest can partition, format, and use it like a physical disk.
VMware virtual disks commonly use the .vmdk extension.
One logical disk can consist of one VMDK file or multiple related files.
Guest-reported capacity and current host filesystem usage are different measurements.
Growable disks use host space as data is written; preallocated disks reserve space at creation.
Removing a disk attachment is not the same as deleting its files.
Move or copy disk files only when the VM is fully powered off, and preserve related files and paths.