Virtual Machine Disk Recovery
When the underlying RAID array fails, the SAN drops a LUN, or a host's local storage dies, every VM on that storage goes offline. We image the failed drives, reconstruct the array, and extract your VMDK, VHD/VHDX, QCOW2, or VDI files from the damaged volume. Free evaluation. No data = no charge.
Why VM Disks Become Unrecoverable Without Physical Recovery
Virtual disk files are just files on a host filesystem. When the physical storage beneath that filesystem fails, the hypervisor cannot read the VM disks regardless of the guest OS or application state inside the VM. Recovery requires working at the physical layer first: imaging degraded drives, reconstructing the array, and then parsing the host filesystem (VMFS, NTFS, ReFS, ZFS, ext4, XFS) to locate and extract the virtual disk files.
Running a RAID rebuild on a degraded array with bad sectors destroys data. Attempting to import a damaged ZFS pool with zpool import -f can overwrite metadata. Booting a VM from a partially recovered datastore without write-protecting the volume first allows the guest OS to modify the filesystem, making a clean recovery impossible. The correct first step is always to image the drives read-only using hardware-level imaging tools before touching anything.
Virtual Disk Formats and Their Recovery Implications
Each hypervisor stores VM disks in a different format with distinct metadata structures, snapshot mechanisms, and allocation strategies. The format determines how we locate and reconstruct the virtual disk from raw storage.
VMDK (VMware ESXi / Workstation)
VMware's VMDK format uses a text descriptor file that references one or more flat extent files. On VMFS datastores, the descriptor and extent typically share the same base name. VMFS5 uses a unified 1MB block size for all allocations. The descriptor specifies the virtual disk type (monolithicFlat, twoGbMaxExtentFlat, vmfsSparse for snapshots, seSparse on VMFS6). Recovery requires parsing the VMFS file descriptor heap to locate the extent data blocks, then following pointer block chains to reconstruct the flat image. For VMFS-specific recovery details, see the VMware ESXi page.
VHD / VHDX (Microsoft Hyper-V)
VHD (legacy, max 2TB) stores data in a footer + BAT (Block Allocation Table) structure. VHDX (current, max 64TB) adds a 4KB-aligned log structure for crash consistency, supports 4KB logical sector sizes, and uses a more resilient metadata region with redundant copies. Hyper-V stores VHDX files on NTFS or ReFS Cluster Shared Volumes (CSVs). AVHDX files are differencing disks created during checkpoints. Recovery from a failed CSV requires reconstructing the underlying Storage Spaces or RAID volume, then parsing NTFS/ReFS to locate the .vhdx and .avhdx files. For Hyper-V checkpoint chain repair, see the Hyper-V recovery page.
QCOW2 (KVM / Proxmox VE / OpenStack)
QCOW2 (QEMU Copy-On-Write version 2) uses a two-level lookup table: L1 table entries point to L2 tables, which in turn point to data clusters (default 64KB). Supports internal snapshots stored as separate L1 tables within the same file, backing file chains (external snapshots), and optional zlib/zstd compression. Proxmox VE typically stores QCOW2 images on ZFS zvols, Ceph RBD, or local LVM-thin volumes. Recovery depends on the backing storage: ZFS pool reconstruction for ZFS-based setups, Ceph OSD recovery for Ceph clusters, or standard LVM metadata repair. For Proxmox-specific ZFS and Ceph scenarios, see the Proxmox VE page.
VDI (Oracle VirtualBox)
VDI (VirtualBox Disk Image) uses a pre-header, header, and block allocation map. Dynamically allocated VDI files grow as the guest writes data; fixed-size VDI files pre-allocate the full virtual disk size. VirtualBox stores VDI files on the host OS filesystem (NTFS, ext4, APFS). Recovery is typically straightforward once the host filesystem is accessible: extract the .vdi file and mount it with qemu-nbd or VirtualBox's own tools. The challenge is getting the host filesystem back when the underlying storage has failed.
How Virtual Machine Storage Fails
VM disk loss almost always traces back to a physical storage failure, not a problem inside the VM itself. These are the scenarios we see most frequently from IT administrators shipping drives to our lab.
RAID Array Degradation
Multiple RAID members fail within the rebuild window. PERC, Smart Array, or software RAID (mdadm, ZFS, Storage Spaces) marks the array as offline. All VMs on the affected LUN or volume go down simultaneously.
SAN LUN Unavailability
iSCSI or Fibre Channel LUN becomes inaccessible after controller failure, firmware corruption, or backend disk pool degradation. The hypervisor reports "device is not accessible" and cannot read the datastore.
Single-Disk Host Failure
VMs running on local storage (a single SSD or HDD in the host) lose access when that drive fails. Common with small Proxmox nodes, lab environments, and VirtualBox setups on workstations.
Accidental Deletion or Reformatting
Administrator deletes a datastore, reformats a LUN, or removes VM disk files through the management console. If the host filesystem has not overwritten the freed space, the virtual disk data may still be present on the physical media.
Corrupted Snapshot Chains
Power loss during snapshot commit or consolidation leaves orphaned delta files. The VM cannot boot because the chain is broken: CID/parentCID mismatches in VMware, missing AVHDX links in Hyper-V, or dangling backing file references in QCOW2.
ZFS Pool Import Failure
Proxmox or FreeNAS hosts lose ZFS pool access after drive failure, controller swap, or corrupted vdev metadata. The pool refuses to import and all zvols (including VM images) become inaccessible. See our ZFS pool recovery guide for the detailed process.
Recovery Process for IT Administrators
This section details the low-level procedures we use. If you are evaluating our technical capability before shipping drives, this is how the work gets done.
1. Drive Imaging (Read-Only, Sector-Level)
Each drive is connected through PC-3000 using SAS HBAs for SAS drives, SATA ports for SATA/SSD, or NVMe adapters for PCIe SSDs. Imaging captures every LBA in read-only mode. For drives with bad sectors, PC-3000 head maps skip damaged heads on first passes and return with adjusted parameters after capturing healthy data. DeepSpar Disk Imager provides hardware-level timeout control for drives that stall during reads. The goal is a complete bit-for-bit image of each drive before any reconstruction begins.
2. Array Reconstruction
PC-3000 RAID Edition reads controller metadata (DDF for PERC controllers, HP-proprietary format for Smart Array, mdadm superblocks for Linux software RAID) from the member images. This metadata contains RAID level, stripe size, member ordering, and parity rotation. When metadata is missing or overwritten, we detect parameters by testing stripe size permutations (64KB, 128KB, 256KB, 512KB, 1MB) and member orderings against known filesystem signatures (VMFS superblock at LBA 0, NTFS boot sector, ZFS uberblocks). The reconstructed array image represents the virtual disk as the controller originally presented it.
3. Host Filesystem Parsing and VM Disk Extraction
With the array image available, we parse the host filesystem directly from the raw image without mounting it read-write. The filesystem type depends on the hypervisor: VMFS for ESXi, NTFS or ReFS for Hyper-V, ext4/XFS/ZFS for KVM/Proxmox. We scan the filesystem metadata for virtual disk file entries (.vmdk, .vhdx, .qcow2, .vdi, .raw), extract each file by following the allocation structures (VMFS pointer blocks, NTFS MFT data runs, ZFS dnode object sets), and verify the extracted file by checking its internal metadata headers and guest filesystem integrity.
4. Snapshot Consolidation and Guest Data Extraction
If the VM had active snapshots, we reconstruct the chain and consolidate the deltas into a single flat image. For VMware, this means reading grain tables from each delta VMDK and merging changed blocks in parent-child order. For Hyper-V, we process AVHDX BAT entries. For QCOW2, we walk the L1/L2 tables from each backing file. The consolidated image is mounted read-only to verify guest filesystem consistency (NTFS, ext4, XFS, APFS) and extract the files your business needs.
What Not to Do When VM Storage Fails
Do Not Rebuild a Degraded RAID Array
If one drive has failed and others have bad sectors, a rebuild will read every sector of every surviving member. When it hits unreadable sectors, the rebuild fails and the controller may drop the array entirely. You go from degraded (recoverable) to offline (harder to recover). Image first, rebuild never.
Do Not Force-Import a ZFS Pool
Running zpool import -f or zpool import -F on a degraded pool with bad drives can overwrite uberblocks and transaction group metadata. This makes offline reconstruction harder. Export the pool if it is still imported, then ship the drives without attempting repair.
Do Not Boot a Partially Recovered VM
Mounting a recovered datastore read-write and booting the VM allows the guest OS to run fsck, chkdsk, or journal replay. These operations modify data on the virtual disk. If the recovery was incomplete, those modifications overwrite sectors you still need. Mount everything read-only until data extraction is complete.
Do Not Swap the RAID Controller
Replacing a failed RAID controller with a different model (or even a different firmware revision of the same model) can cause the new controller to re-initialize the array with its own metadata layout. This overwrites the existing DDF or proprietary metadata blocks. If the controller died, ship the drives as-is.
VM Disk Recovery Pricing
Same transparent model as every other recovery we perform. Per-drive imaging based on each drive's condition, plus a reconstruction fee for multi-drive arrays. VM disk extraction and snapshot consolidation are included in the reconstruction fee.
| Component | Price Range | When It Applies |
|---|---|---|
| Logical / Firmware Imaging (per drive) | $250-$900 | Drive is accessible but has firmware or filesystem corruption |
| Mechanical Recovery (per drive) | $1,200-$1,50050% deposit | Drive clicking, not spinning, or has head/motor failure |
| Array Reconstruction + VM Extraction | $400-$800per array | RAID reconstruction, host filesystem parsing, VM disk extraction, snapshot consolidation |
No Data = No Charge: If we recover nothing from your VM environment, you owe $0. Free evaluation, no obligation.
NDA available for corporate recoveries. All drives remain in our Austin, TX lab under chain-of-custody documentation throughout the process.
Virtual Machine Disk Recovery FAQ
Which virtual disk formats can you recover?
Can you recover split-extent VMDKs or sparse files?
What if my VM had active snapshots when the storage failed?
Do I need to send the entire server or just the drives?
How much does virtual machine disk recovery cost?
Can you recover encrypted virtual disks?
Data Recovery Standards & Verification
Our Austin lab operates on a transparency-first model. We use industry-standard recovery tools, including PC-3000 and DeepSpar, combined with strict environmental controls to make sure your hard drive is handled safely and properly. This approach allows us to serve clients nationwide with consistent technical standards.
Open-drive work is performed in a ULPA-filtered laminar-flow bench, validated to 0.02 µm particle count, verified using TSI P-Trak instrumentation.
Transparent History
Serving clients nationwide via mail-in service since 2008. Our lead engineer holds PC-3000 and HEX Akademia certifications for hard drive firmware repair and mechanical recovery.
Media Coverage
Our repair work has been covered by The Wall Street Journal and Business Insider, with CBC News reporting on our pricing transparency. Louis Rossmann has testified in Right to Repair hearings in multiple states and founded the Repair Preservation Group.
Aligned Incentives
Our "No Data, No Charge" policy means we assume the risk of the recovery attempt, not the client.
Technical Oversight
Louis Rossmann
Louis Rossmann's well trained staff review our lab protocols to ensure technical accuracy and honest service. Since 2008, his focus has been on clear technical communication and accurate diagnostics rather than sales-driven explanations.
We believe in proving standards rather than just stating them. We use TSI P-Trak instrumentation to verify that clean-air benchmarks are met before any drive is opened.
See our clean bench validation data and particle test videoRelated Enterprise Recovery Services
VMFS datastores, vSAN clusters
VHD/VHDX, CSV reconstruction
ZFS, Ceph, QCOW2 extraction
RAID 0, 1, 5, 6, 10 arrays
Dell, HP, IBM enterprise servers
Synology, QNAP, TrueNAS
Dell EMC, NetApp, HPE arrays
SQL Server, MySQL, PostgreSQL, MongoDB
VM storage down? Ship us the drives.
Free evaluation. No data = no charge. Label drive bays and ship to Austin, TX.