VMware ESXi and vSphere Cluster Management
Virtual Hard Disk Files in VMware Workstation Player
Learn how VMware Workstation Player uses VMDK files, virtual disk controllers, host storage, capacity limits, and single-file or 2 GB split-disk layouts.
A virtual hard disk is a file-backed disk device presented to a virtual machine. The guest operating system treats it much like a physical disk: it can contain the operating system, installed applications, configuration files, and user data.
The guest operating system runs inside the virtual machine. The host operating system runs VMware Workstation Player and stores the virtual machine's files. The guest sees a virtual disk device, while the host stores that device as one or more files.
What a Virtual Hard Disk Does
A virtual hard disk provides persistent storage for a guest. When the virtual machine is powered off and started again, the guest's files remain in the virtual disk files stored by the host.
- The guest operating system can be installed on the virtual disk.
- Applications and their supporting files can be stored there.
- User documents, databases, downloads, and other data can occupy the disk.
- The guest can partition and format the disk using its normal disk-management tools.
Do not confuse the guest disk with the physical location holding it. For example, a guest may see a 500 GB virtual disk, while the host stores that disk in a VMDK file on a host SSD. The virtual capacity and the host file arrangement are related, but they are not the same concept.
VMDK Files and Naming
VMDK is VMware's virtual disk file format. VMware virtual disk files commonly use the .vmdk extension.
A normal naming convention is based on the virtual machine name. For example, a virtual machine named Windows 8.1 VM might have a primary disk named Windows 8.1 VM.vmdk. A generic form is:
<VM-NAME>.vmdkThe exact names can differ. A VM with several virtual disks may have separate names for each disk, and a split disk may use several extent files. Keep all files belonging to a virtual disk together when moving or copying the VM.
Virtual Disk Controllers
A controller is the virtual hardware interface through which the guest accesses a virtual disk. VMware Workstation Player can present a disk through IDE, SATA, or SCSI-style virtual hardware, depending on the VM configuration and guest compatibility.
Controller selection affects whether the guest recognizes the disk and has a suitable driver for it. A disk file stored on a host SATA SSD does not automatically mean that the guest disk is attached through a virtual SATA controller.
When adding a disk, choose IDE or SATA when appropriate for the guest. Choose SCSI only when the guest operating system has compatible support for the selected LSI Logic or BusLogic adapter.
Where VMDK Files Are Stored
VMDK files reside on storage accessible to the host operating system. For practical performance, place them on fast-access storage media with enough free space for the VM and its expected growth.
Possible host storage locations include host physical disks connected through IDE, SATA, or SCSI interfaces, as well as other suitable fast-access storage media. These interfaces describe how the host accesses its physical storage. They do not identify the controller that VMware exposes to the guest.
Virtual Disk Capacity
The supported virtual disk capacity is up to 8 TB. This is the capacity presented to the guest, not necessarily the size of a single file on the host.
A configured 8 TB virtual disk could be represented by one large file or by multiple files, depending on the selected layout and host file-system constraints. Capacity planning must consider both the guest's expected data needs and the host's available storage. The host needs enough practical space to store the virtual disk and other VM files.
Single-File and Multi-File Virtual Disks
One virtual disk can be stored as one file or as multiple files. The disk size, selected VMware option, and limitations of the host operating system or file system can influence the layout.
The 2 GB split-disk option divides the virtual disk into files limited to 2 GB. Its main purpose is compatibility with older file systems that cannot store a file larger than 2 GB. On modern storage, a single-file layout is usually easier to handle when the destination supports it. Split files can be preferable when legacy portability is important.
Configuration Decisions When Adding a Disk
Adding a new virtual hard disk is the next common management task after understanding VMDK files. During the process, decide:
- Capacity: Choose enough virtual capacity for the guest's operating system, applications, and expected data.
- Controller type: Select IDE, SATA, or a supported SCSI adapter based on guest driver compatibility.
- Storage location: Select host-accessible, fast-access storage with sufficient available space.
- File layout: Choose a single file, multiple files, or files limited to 2 GB when legacy file-system portability is required.
- Guest setup: After attachment, allow the guest to detect the disk and initialize, partition, and format it when appropriate.
A newly attached disk may be visible to the guest but still unavailable for storing files. The guest normally must initialize it, create a partition or volume, and format that volume with a suitable file system. These operations are performed inside the guest operating system.
Practical Examples
Standard disk naming
A VM named Windows 8.1 VM can use Windows 8.1 VM.vmdk for its primary virtual disk. If the VM has additional disks or uses split extents, more related VMDK files may appear.
Choosing a controller
Use SATA or IDE when the intended guest supports the selected virtual hardware. Use SCSI with LSI Logic or BusLogic only when the guest includes a compatible driver. A SCSI disk without the required driver may not appear in the guest.
Moving a disk to a legacy file system
Before transferring a virtual disk to a destination that cannot store files larger than 2 GB, choose the 2 GB split-file layout. The disk remains one virtual disk to the guest, even though the host stores it in several segments.
Adding data storage
Add a second virtual disk for application data, select its capacity and controller, and place its files on suitable host storage. After the guest detects it, initialize and format the disk before saving application data.
Planning a large volume
A VM that needs a large data volume can use a virtual disk configured up to the supported 8 TB maximum, provided the host storage can accommodate the required files and the guest operating system supports the intended volume.
Troubleshooting
The guest does not recognize a newly attached SCSI disk
The guest may lack a compatible driver for the selected SCSI adapter. Install or enable the appropriate LSI Logic or BusLogic support when available, or attach the disk through a compatible IDE or SATA controller.
A virtual disk cannot be copied to an older file system
The destination may not support the size of the VMDK file. Use a virtual disk layout split into files limited to 2 GB before making the transfer, and copy every related disk file.
Host storage and guest controller appear confusing
Identify the two layers separately. First locate the VMDK on the host's physical storage. Then check which virtual controller—IDE, SATA, or SCSI—the VM presents to the guest.
The guest sees the disk but cannot store files on it
The disk may not yet be initialized, partitioned, or formatted. Complete the guest operating system's disk setup, then assign a usable volume or mount point as required.
The host runs out of practical storage space
Review the virtual disk capacity, the selected file layout, and the free space at the host storage location. Reduce the planned capacity when appropriate, choose a more suitable host location, or provide additional host storage.
Exam-Relevant Notes
- VMDK is the VMware virtual disk file format and normally uses the
.vmdkextension. - The guest sees a disk device; the host stores that device as one or more files.
- IDE, SATA, and SCSI describe virtual controllers exposed to the guest, not necessarily the host storage interface.
- SCSI requires suitable guest support for the selected LSI Logic or BusLogic adapter.
- Virtual disk capacity can be up to 8 TB, while the number and size of host files can vary.
- A 2 GB split disk improves compatibility with older file systems but creates more files to manage.
- A newly added disk usually needs guest-side initialization, partitioning, and formatting before use.
For the related management task, see virtual hard disk files and disk configuration.