A small plain-text file containing configuration data, disk geometry, adapter type, and parental chains. This is the "header".
If you have a recent backup of the VMDK file or the virtual machine, you can restore it. This is often the quickest solution if the corruption is due to a recent change or addition.
The vmware.log file will explicitly state: DISKLIB-LINK : "VM.vmdk" : failed to open (The file is not a virtual disk). 3. Technical Root Causes Corruption typically occurs due to: Improper Shutdowns: Power loss during metadata writes. vmdk header file corrupt
The VM appears in vCenter, but its disk size shows as 0 MB .
In the realm of enterprise IT and personal virtualization, few error messages provoke as much immediate concern as “VMDK header file corrupt.” The Virtual Machine Disk (VMDK) file is the backbone of VMware virtual machines, functioning as the virtual hard drive that stores the guest operating system, applications, and user data. When its header becomes corrupted, the virtual machine often fails to power on, refuses to mount, or becomes entirely inaccessible. Understanding the anatomy of this error, its root causes, and the available recovery methodologies is essential for any system administrator or virtualization user. A small plain-text file containing configuration data, disk
Recovering from a VMDK header error requires a methodical approach. The first step is always . Using VMware’s vmkfstools command-line utility, an administrator can run vmkfstools -x check /path/to/disk.vmdk to analyze the header and extent consistency. If the check reveals a corrupted descriptor, the next line of defense is restoring from backup —the most reliable solution. In the absence of recent backups, header reconstruction becomes necessary. Since the descriptor file is human-readable (in monolithic flat or two-file VMDK formats), an advanced user can manually recreate the header using known disk geometry from the virtual machine’s logs or by copying a header from a healthy, similarly configured virtual disk. For example, a base template header can be edited to match the correct extent name and disk size. Alternatively, third-party recovery tools (e.g., DiskInternals VMFS Recovery, StarWind V2V Converter) can attempt to parse the raw extent and generate a new valid header. A last resort is to use a hex editor to salvage any intact header metadata from a partially overwritten file.
VMDK header corruption rarely occurs spontaneously. Instead, it typically results from one of several identifiable scenarios. are a leading cause: if a virtual machine is forcefully powered off while writing metadata to the disk, the header can be left in an inconsistent state. Storage subsystem failures , such as a network-attached storage (NAS) disconnect or a corrupted datastore, can also truncate or scramble the header. Snapshot mismanagement is another frequent culprit—deleting a snapshot improperly or running out of space during a snapshot commit can break the descriptor chain. Additionally, human error , such as accidentally editing or deleting the .vmdk descriptor file via the command line, directly introduces corruption. Finally, malware or antivirus scans that lock or quarantine VMDK files in real-time can inadvertently damage header integrity. This is often the quickest solution if the
Underlying VMFS (Virtual Machine File System) issues that zero out small blocks. 4. Recovery Methodology: Manual Reconstruction
Example: A 40 GB disk will show exactly 42,949,672,960 bytes. Step 2: Calculate Disk Geometry
If you are using Type-2 hypervisors like VMware Workstation, the header may be embedded at the very beginning of a single monolithic VMDK file rather than split into two files. [Solved] Recovering corrupt vmdk file - virtualbox.org