Sometimes you need the data inside a VMDK file, but the virtual machine that owns it is unavailable. The guest OS may fail to boot, the VM may be corrupted, or you may only have a copy of the disk from another host or a backup. This guide covers 3 ways to open a VMDK file in VMware ESXi and VMware Workstation, and how to back it up before you start.
What Are VMDK Files?
What a VMDK looks like on disk depends on the VMware product:
VMware ESXi: each virtual disk is made of two files. vmname.vmdk is a small text descriptor that records the disk’s geometry and settings, and vmname-flat.vmdk holds the actual data. The vSphere Client datastore browser often shows them as one disk, but you need both files whenever you copy or move the disk.
VMware Workstation: a virtual disk is usually a single .vmdk file, or several 2 GB files such as vmname-s001.vmdk if the disk was split when it was created.
Snapshots: a VM with snapshots also has delta disks such as vmname-000001.vmdk. These record only the changes made after the snapshot and depend on the base disk.
VMDK files can be thick provisioned (all space allocated up front) or thin provisioned (space allocated as data is written). The methods below work for both types.
Before You Open: Back Up the VMDK First
Opening or mounting a VMDK in the wrong mode can change its contents, break a snapshot chain or corrupt the file system inside it. Copy the disk before you try any of the methods below, so you always have an untouched original to go back to.
Prepare for the copy
Power off the VM with Shut Down Guest OS in the vSphere Client. Copying the disk of a running VM by hand can capture inconsistent data, and ESXi usually locks the disk anyway.
If the VM must stay online, don’t copy its files manually. Use backup software that reads the disk through a quiesced snapshot instead (see the Vinchin section below).
Also copy the VM’s .vmx configuration file if you may need to rebuild the VM later.
Copy the VMDK files in the vSphere Client
Log in to the vSphere Client and go to Storage. Select the datastore and open the Files tab.
1. Open the folder named after the VM.
2. Select the .vmdk file and click Copy to to copy it to another datastore or folder, or click Download to save it to your local machine.
3. Make sure both the descriptor (vmname.vmdk) and the data file (vmname-flat.vmdk) are in the destination, and that the size of the data file matches the original.
Tip: Browser downloads of very large VMDK files can fail or time out. For large disks, use Copy to between datastores, or clone the disk from the ESXi shell with vmkfstools -i. If local storage is not enough, save the copy to a NAS or other network storage.
Method 1: Open VMDK with a Live DVD Even When the Guest OS Fails
This technique needs a VM that can boot from a DVD disc, then you may launch your VM using the ISO image as a DVD disc, mount partitions of virtual disks, and copy files to a USB hard drive connected to the VM, your host computer, or other machines via a network. This method applies to VMware ESXi/Workstation/Player (here is ESXi).
1. Download the Ubuntu ISO installation image.
2. Log in to vSphere Client and access the VMs in the Hosts and Clusters section. Right-click the VM and choose Edit Settings…
3. In the CD/DVD Drive section, select Datastore ISO File. Then go to CD/DVD Media, and click Browse to designate the ISO file.
4. Boot the VM from ISO file and choose Try Ubuntu Without Installing. After that, open the Terminal. Enter the following commands.
Gain toot privilege:
sudo -i
Find the list of hard drives available:
ls -al/dev/sd*
Make the directories as mount points for partitions:
mkdir/mnt/win-disk1
mkdir/mnt/win-disk2
Mount partitions:
mount/dev/sda1/mnt/win-disk1/
mount/dev/sda2/mnt/win-disk2/
List the mounted partitions files:
ls -al/mnt/win-disk2/
ls -al/mnt/win-disk1/
5. Attach the USB hard drive to the ESXi host with a USB pass-through and copy the required VMDK files. Or use SMB (CIFS) share and copy virtual disk contents to another target destination via a network.
Method 2: Mount a VMDK File to a VMware ESXi or Workstation VM
This way requires the VMDK connection to an existing virtual machine with running OS. VMDK files can be added as an additional virtual disk to the VM.
Mount a VMDK file to an ESXi VM
1. In the vSphere Client, navigate to Storage >Datastore Browser> select the VMDK file> click Copy to.
2. Specify the location datastore, then go back.
3. In the Hosts and Clusters section, right-click the VM and choose Edit Settings.
4. Click ADD NEW DEVICE on the top right of the pane> choose Existing Hard Disk.
5. Choose the copied VMDK files and click OK.
6. In Windows Explorer, open the mounted drive and copy VMDK contents.
Mount a VMDK file to a Workstation VM
1. In the vSphere Client, navigate to Storage >Datastore > File> Download (then unzip the files in the ZIP archive).
2. In VMware Workstation, select the VM and click Edit the virtual machine settings.
3. Click Add in the wizard > Hard Disk > SCSI > Use an existing virtual disk > locate the downloaded VMDK > click Finish.
4. Boot the Windows Disk Management, alter the virtual disk state to online, then give a drive letter to a partition and browse the files.
Method 3: Access a VMDK File Without Attaching It to a VM
Mount VMDK files to Workstation while the VM is Powered off in Windows
1. Log in to Workstation. Go to File > Map Virtual Disks > Browse.
2. Check the Open file in read-only mode (recommended) in the checkbox to avoid unnecessary virtual disk damage. The default Drive Z: means the drive is automatically launched in Windows Explorer following the mapping. Click OK.
3. Verify the delta virtual disk connected to the first snapshot in the wizard and click Disconnect Virtual Disk.
Mount a Workstation VMDK file on a Linux host while the VM is Powered off
1. In VMware Workstation, go to File > Mount Virtual Disks > Browse. Select the VMDK file.
2. In the Linux file system, create a directory to mount the VMDK virtual disk.
mkdir/mnt/vmdk/
chown -R userX: groupX/mnt/vmdk/
3. Choose the target directory and check Mount read-only option.
4. In Linux explorer, open mnt / vmdk / directory and find the files on VMDK disk. Unmount the VMDK image file from Linux once not in use.
5. Enter the commands to mount the VMDK on Linux. Then click Disconnect Virtual Disk.
vmware-mount/media/userX/vms/vmname/vmdiskname.vmdk/mnt/vmdk
Protect VMware VMs and Restore Files Without Opening VMDKs
To prevent unbootable virtual machines or corrupted VMDK files caused by malware, system upgrades, or unexpected failures, regular VM backup is essential. Vinchin Backup & Recovery provides centralized protection for 19+ virtualization platforms including VMware, oVirt, Oracle OLVM, and XenServer, as well as databases, Linux and Windows servers, and NAS systems.
It supports automated agentless VMware backup with flexible schedules and email alerts, while intelligent backup strategies such as incremental backup, data deduplication, compression, and HotAdd transport help reduce backup size and improve transmission efficiency.
Here shows an example of backing up VMware ESXI in Vinchin:
1. Select a backup source
Navigate to VM Backup > Backup in the Vinchin backup server, then select the backup source (s) from expanded VMware VMs added to the software.
2. Select a backup destination
Specify the backup destination for the VM. Select the backup node and storage associated with it from the dropdown lists.
3. Customize backup strategies
Configure backup strategies. Customize backup schedules, data reduction options, retention mode (GFS or normal settings), transmission modes, and more here to streamline VMware backup effortlessly.
4. Submit the job
review all the configurations and click Submit.
Vinchin Backup & Recovery has been widely recognized as a robust and reliable VM backup and recovery solution. It offers a 60-day free trial with full features; In addition, its cross-platform V2V migration feature allows administrators to migrate workloads between different hypervisors through simple recovery operations, while 15-second instant recovery helps quickly restore failed VMware VMs directly from backup repositories to maintain business continuity.
Click the Download button below to see how fast, simple, and secure its backup feature is.
FAQs Related to Opening VMDK in VMware
Q1: What should I do if the VMDK file is corrupted or the VM cannot boot?
If the disk is readable, try Method 1 to boot from a live DVD and copy your data out. If the VMDK itself is damaged, restore the VM or its files from a backup. For damage that appears after a restore, you can find the causes for restored VMDK coming back corrupted on VMware vCenter.
Q2: Can I open a VMDK file while the VM is running?
Not directly. ESXi locks the disks of a running VM, so they can't be attached to another VM or mapped on the host. Power off the VM first, work on a copy of the disk, or restore the files you need from a backup.
Q3: Why is my VMDK file locked?
A VMDK is usually locked because the VM is powered on, another VM or backup job is using the disk, or a lock file (.lck) was left behind after a crash. Power off the VM and wait for running jobs to finish before you try again. Remove stale lock files only when you are sure nothing is using the disk.
Q4: Should I back up VMware VMs before opening or mounting VMDK files?
Yes. Creating VM backups before accessing or modifying VMDK files helps prevent data loss caused by accidental corruption, misoperations, or system failures.
Conclusion
When a VM is unavailable, you can still reach the data in its VMDK files by booting from a live DVD, attaching the disk to another VM or mapping it directly in VMware Workstation. Whichever method you use, back up the VMDK first and mount it in read-only mode whenever you can.
To avoid opening VMDKs by hand at all, protect your VMs with Vinchin Backup & Recovery. It backs up running VMware VMs without agents and lets you restore single files or whole VMs in minutes.
