Data Recovery for VMDK, VHDX and Other Virtual Disks
Datastrophe assesses virtual disk faults without altering the source, reconstructs the relevant storage layers and supplies files that have passed usability checks.
Initial assessment
Copy the datastore and physical storage before analysis
Protect the datastore and physical media first, then locate the fault across the virtual disk, snapshot chain and guest system on working copies.
Copy the datastore and its underlying physical storage before attempting virtual-disk repair. A damaged VMDK, VHDX, VHD or QCOW2 file may depend on VMware, Hyper-V, Proxmox, VirtualBox or KVM metadata, while the datastore itself may sit on unstable disks or RAID. Protected copies preserve both layers before snapshot or guest reconstruction begins.
The source is handled as technical evidence. Its original state is retained, write activity is prevented, and the storage layers needed for recovery are identified before an imaging or reconstruction method is selected. This approach helps distinguish logical damage, media failure, structural corruption and incidents involving more than one fault.
Returning the hardware or virtual environment to service is not the aim. Recovery produces a practical copy of the data that remains available, while identifying any regions lost to destruction, later writes or encryption for which no key is available.
For VMDK and VHDX sets, locating the main disk file is only part of the task. The relationship between its descriptor, extents, parent, deltas and guest file system must also be rebuilt. An absent delta or mismatched CID can break a virtual machine even when most underlying blocks remain readable.
- Map descriptors, extents and snapshot deltas
- Distinguish the datastore from the virtual disk and guest
- Set priorities for SQL databases, shared data and application files
Scope of the initial technical review
The original state is protected while the relevant storage layers and safe read path are established. This allows the data recovery laboratory to separate logical damage, failing media, broken structures and combined faults.
A clear recovery boundary
The purpose is to retrieve usable data, not return suspect storage to production. Unreadable, overwritten or inaccessible encrypted areas are reported as limits.
Risk indicators
Follow every snapshot parent, delta and content identifier
Map the complete parent-and-delta chain before mounting or consolidating it; one missing or mismatched component can invalidate the apparent current state.
Every snapshot parent, delta and content identifier must be followed before a current virtual-disk view can be trusted. A missing delta, mismatched CID, incomplete VHDX checkpoint or broken QCOW2 backing chain can stop a virtual machine even when the base disk remains readable. Modification times, descriptors and expected sizes help establish the actual sequence.
What happened before and after the loss is as important as the error shown on screen. Impact, power interruption, deletion, formatting and an attempted rebuild require different responses. Earlier recovery attempts may also have replaced data or changed metadata needed to interpret the disk.
Continuing to run the affected system can reduce the recoverable scope. In a logical incident, routine writes may reuse blocks belonging to deleted files; where hardware is failing, repeated reads can make weak regions deteriorate further.
The technical review separates datastore failure from corruption of the virtual disk and damage inside the guest. VMFS, NTFS, ext4, XFS, VHDX logs and QCOW2 backing chains have distinct journals, offsets and consistency records, so they cannot be treated as a single ordinary partition.
- Review parent CIDs, grain tables and VHDX logs
- Assess VMFS, QCOW2, VHDX or VMDK before extracting data
- Choose between a reconstructed VM and a targeted export
How the incident sequence affects recovery
Impact, a power event, deletion, formatting and attempted reconstruction leave different evidence. Any action already taken may also have written to the source or altered useful metadata.
Safest immediate action
Shut down activity on the affected storage. New writes threaten deleted data, while repeated reads can worsen a physical fault.
Source protection
Do not consolidate a virtual machine that no longer starts
Avoid consolidation, test boots, deleted deltas, partial copies and in-guest repair until the complete virtual disk set has been assessed.
Do not consolidate snapshots without a map of the chain, test-boot the machine, remove delta files, copy only selected components or run automatic repair in the guest. Each action changes evidence that may be required for diagnosis and can leave a previously recoverable set incomplete.
Automated repair may reset logs, relocate fragments, rewrite file-system structures or create files that no longer agree with their metadata. Stop exploratory work and record exactly which commands, boots or copies have already been attempted.
Datastrophe uses controlled reads and separate working copies. The source is not used for experimentation, allowing competing reconstruction options to be tested without consuming weak media or obscuring the original technical evidence.
Premature consolidation may embed an error permanently in the snapshot chain. Parent and delta files, modification times and expected sizes are mapped first, so a coherent view can be assembled without writing over the source state.
- Keep the descriptor, extents and every delta together
- Examine the virtual format and datastore before extraction
- Record which databases, shares and application files matter most
Checks before any reconstruction
Automatic tools can clear journals, rewrite structures and move fragments. Record previous activity, then stop changes while the full set is reviewed.
How the source is protected
Controlled acquisition and working copies allow reconstruction options to be compared without placing the original data at further risk.
Layer analysis
VMDK, VHDX and dynamic disks each carry distinct metadata
A virtual disk case can involve container metadata, snapshots, a datastore, the guest file system and application data, each requiring its own checks.
Analysis may span VMDK, VHDX or QCOW2 structures, snapshot metadata, VMFS and the NTFS or ext4 guest file system, through to SQL databases. The observed damage determines whether work begins with blocks, allocation metadata, file-system records, application structures or several layers in sequence.
A directory tree that can be browsed is not evidence that its contents are sound. Equally, a blank management interface does not prove the data has vanished. Logs, signatures, tables, indexes, snapshots and surviving fragments may still support a useful, documented result.
Work proceeds from the source condition to virtual container structures, then to the guest file system and priority content. This ordered review reduces the chance of presenting a visually complete file list that does not meet the operational need.
- Validate CIDs, allocation tables and VHDX journals
- Keep datastore, container and guest evidence distinct
- Provide either a rebuilt machine or the required data export
Evidence is not the same as usability
Browsable folders do not confirm healthy files, and an empty interface does not confirm total loss. Surviving logs, indexes and fragments must be interpreted and tested.
A layer-by-layer method
The media and read quality are established first, followed by logical structures and finally the data identified as important.
Recovery process
Mount a read-only copy before restarting the guest system
Use a read-only reconstructed copy to inspect the guest state before any boot, repair or application start can create new writes.
Mount a reconstructed copy read-only before any attempt to restart the guest operating system. A boot can replay journals, modify services, write temporary files and change the very state being assessed. Read-only examination first establishes whether partitions, file systems and priority data are coherent enough for a later isolated start-up.
If the source storage is unstable, readable regions are secured first. For logical damage, write activity is stopped while deleted or corrupt structures are located. Where several layers are affected, the least destructive dependency is addressed before later reconstruction.
Representative recovered files are then opened and checked. Dates, sizes, internal structure or comparison data are used where available, because the volume of extracted bytes alone says little about whether the result can be used.
Dynamic disks require careful interpretation. Grain tables, bitmaps, sparse extents and thin provisioning can reference blocks that are absent or were never allocated, so file size alone cannot establish that a virtual disk is complete.
- Preserve all descriptors, extents and snapshot components
- Review the container format before extracting guest data
- Test priority databases, shared folders and application content
Selecting the recovery order
Unstable storage is imaged around weak regions; logical damage is protected from further writes; multi-layer cases are handled in the least destructive dependency order.
Testing the recovered result
Samples of important content are opened and, where possible, checked against dates, structures or reference copies. Recovered capacity is not a substitute for usable files.
Data priorities
Databases and services require application-level consistency
Identify the databases, shared content, application files, exports and virtual machines that must be usable first, especially when the source is unstable.
Business databases, shared folders, application data, exports and important virtual machines often require first attention. Listing them early changes the search order, allowing recent or critical content to be checked before an exhaustive extraction has completed.
Priorities are particularly valuable when the underlying device is deteriorating or only a small part of a large system is operationally important. A focused scope can also limit unnecessary access to unrelated sensitive content.
Final review distinguishes files that open and function from partial files and entries that were only detected. A name in an inventory is not treated as recovered data until its content can be read or used in the required context.
Companion files can be decisive when the disk originated in Hyper-V, VMware, Proxmox or KVM. VMX, VMCX, XML, hypervisor logs, snapshot metadata, OVF exports and manifests may establish the reconstruction sequence.
- Use CIDs, allocation metadata and VHDX logs to confirm context
- Check the virtual format before committing to extraction
- Select a reconstructed VM or focused export to suit the need
When a focused search helps
Prioritisation is useful on degraded or high-capacity storage and reduces review of unrelated sensitive data while the required content is checked.
What a verified result means
Usable files, partial files and detections are reported separately. Recovered status depends on content that can be opened or applied, not its appearance in a list.
Reconstruction record
Document the reconstructed version and every missing block
Name the reconstructed snapshot state, source chain, conversion and every known missing block so the result can be interpreted and reproduced.
The delivered result must identify exactly which virtual-disk version was reconstructed. Record the base image, every parent and delta used, the relevant identifiers, the snapshot time and any substitution or conversion performed during recovery.
Missing or unreadable blocks are mapped rather than hidden behind a successful mount. Their location can affect a file system, database, application log or unused guest area very differently, so the report links technical gaps to the data that was actually checked.
Output may be a rebuilt image, converted disk or targeted file set. The format, source chain and departure from the original environment remain explicit, and access to guest data stays within the agreed recovery scope.
Files are opened within the guest context where practical, while extracted databases are assessed for consistency. This prevents a normal-looking directory tree from concealing missing transactions, permissions or records.
- Retain the full chain needed to explain the recovered state
- Validate guest data separately from the datastore and container
- Focus checking on the databases and application files requested
Identify the recovered version
The report ties the output to a specific base image, snapshot chain and point in time. This prevents a valid older state from being mistaken for the latest guest state.
Map missing blocks to practical impact
Unreadable extents, absent snapshots, unavailable keys and inconsistent databases are recorded plainly and related to the affected guest files or services where evidence permits.
Case preparation
Provide the VM inventory, hypervisor and snapshot chain
Provide the storage details, incident history, symptoms, earlier actions and a concise priority list so the assessment stays focused on the real requirement.
Prepare the storage model and capacity, symptoms, incident date, actions already taken and the files needed most. Screenshots or photographs of error messages and the physical storage condition can provide useful context for the assessment.
Retain associated equipment and records, including enclosures, cables, adapters, power supplies, replaced drives, configuration files and partial backups. An apparently minor item may link a snapshot to its parent or confirm the timing of a change.
A useful case description states what occurred, which recovery or repair steps were tried, which data matters and what form of partial result would still be useful. These facts make the assessment more precise.
Handover may comprise extracted files, a reconstructed virtual disk, a specific database export, an application folder set or a review copy. The format is selected for the intended use and the actual limits of the snapshot chain.
- Supply relevant CIDs, allocation metadata and VHDX logs
- Keep the entire VMDK, VHDX or QCOW2 set available
- State whether a rebuilt VM or selected export is required
Items worth retaining
Keep enclosures, cables, adapters, power supplies, previous drives, configuration records and partial backups. They may resolve storage relationships or incident timing.
Describe the required outcome
Record what happened, what has already been tried, which data is essential and which partial result would remain useful.
FAQ
Frequently asked questions
What is the first step after a virtual disk failure?
Stop activity that may write to the affected storage, record the symptoms and incident sequence, retain every disk and snapshot component, and identify the files needed most. Repeated attempts can alter useful metadata or make weak media less readable.
Can every file be recovered from a damaged virtual disk?
No outcome can be confirmed before assessment. Recoverability depends on readable storage, later writes, surviving metadata, the completeness of the snapshot chain and access to any encryption keys. The work targets the best supportable result and reports what cannot be verified.
Why does the data recovery laboratory ask for priority files?
Priority databases, shared folders and application data direct the diagnostic assessment and validation work. They allow the most important outcome to be tested early, particularly when the source is fragile or contains a large volume of data.
Can the original storage return to production after recovery?
Recovery is intended to extract data, not certify failed or corrupted storage for reuse. Recovered content is placed on healthy storage, and the source should be regarded as unreliable for production.
How are incomplete or uncertain results reported?
The report identifies overwritten or unreadable regions, unstable components, missing metadata, partial files, inconsistent databases and inaccessible encryption. Detected items are kept distinct from files whose usability has been checked.
Media
Other expertise
- Data Recovery for Failed Internal Hard Drives Professional recovery from internal hard drives affected by mechanical damage, unreadable sectors, lost partitions, formatting or firmware faults.
- Recover Data From a Damaged External Hard Drive Recovery of files from external hard drives affected by impact, damaged USB connections, missing partitions, deletion or unstable media.
- Recovering Files from Failed SSD and NVMe Devices Controlled recovery from inaccessible SSD and NVMe devices affected by controller, NAND, firmware, power, encryption or volume faults.
- Recover Data From a Damaged or Unreadable USB Drive Professional file recovery from USB drives with broken plugs, failing NAND, corrupted structures, missing folders or recognition faults.
- Recover Files From a Failed or Formatted Memory Card Recovery of photos, video and other files from SD, microSD and CompactFlash cards affected by formatting, corruption, read errors or flash faults.
- Recovering Data from a Failed Laptop Recover files from laptops affected by startup failure, impact, liquid, inaccessible accounts, internal drive faults or soldered storage.
- Recovering Data from Mac Computers and Apple Storage Controlled recovery of usable files from Mac computers, APFS volumes, FileVault storage, Apple SSDs and separated Fusion Drives.
- Recovering Data from a Tablet or iPad Recover local photos, documents and application data from tablets with startup, screen, storage, access or synchronisation faults.
- Recovering Data from RAID, NAS and Storage Arrays Recovery of data from RAID, NAS and server arrays affected by disk faults, unavailable controllers, degraded volumes or unsuccessful rebuilds.
- Recovering Critical Data from Business Servers Recovery of usable data from failed servers, RAID arrays, SQL databases, shared storage, virtual machines and damaged volumes.
- CCTV Footage Recovery From NVR, DVR and XVR Systems Recovery of security camera footage from NVR, DVR and XVR systems affected by damaged indexes, storage faults, unreadable exports or timestamp errors.
- Inside an ISO 5 Clean Room for Hard Drive Recovery How an ISO 5 Class 100 clean room supports hard drive recovery by controlling dust around exposed heads, platters and internal parts.
Data Recovery for Failed Internal Hard Drives 
Recovering Files from Failed SSD and NVMe Devices 
Recover Data From a Damaged or Unreadable USB Drive 
Recover Files From a Failed or Formatted Memory Card 
Recovering Data from a Failed Laptop 
Recovering Data from a Tablet or iPad 
Recovering Data from RAID, NAS and Storage Arrays 
Recovering Critical Data from Business Servers 
CCTV Footage Recovery From NVR, DVR and XVR Systems 
Inside an ISO 5 Clean Room for Hard Drive Recovery Diagnostic assessment
Unsure about a storage device or fault?
Datastrophe assesses the risk before any recovery attempt and points you towards the safest next step.