Lab Operational Since: 17 Years, 7 Months, 19 Days·Facility Status: Fully Operational & Accepting New Cases·
Lab Operational Since: 17 Years, 7 Months, 19 Days·Facility Status: Fully Operational & Accepting New Cases·
Lab Operational Since: 17 Years, 7 Months, 19 Days·Facility Status: Fully Operational & Accepting New Cases·
Enterprise Virtualization Recovery
VMware and Hyper-V Recovery from Corrupted RAID Arrays
This is server RAID recovery for the compound case: the physical array under your VMFS datastore or Hyper-V Cluster Shared Volume has failed, so the .vmdk or .vhdx cannot be reached until the array is reconstructed first. We image every surviving member read-only, rebuild the geometry in software, then extract the VMs. Free evaluation. No data = no charge.
The Compound Failure: A Failed Array Under a Virtual Datastore
When the RAID array beneath a VMFS datastore or Hyper-V CSV fails, the .vmdk or .vhdx files cannot be read. Recovery runs strictly in order: image every surviving member read-only, reconstruct the array geometry virtually, extract the VM container, then mount the guest filesystem read-only.
A virtual machine is a file inside a file inside a volume inside an array. The guest data lives in a guest filesystem, which lives inside a .vmdk or .vhdx container, which lives on a host filesystem (VMFS, NTFS, or ReFS), which lives on a RAID volume spanning several physical members. A normal VMDK or VHDX recovery assumes the array and host filesystem are intact and mountable. This page covers the case where they are not: the array itself has dropped enough members to fail, and every layer above it is unreadable as a consequence.
Why Two Recovery Problems03/10
Why is a Failed Array Under a Datastore Two Stacked Recovery Problems?
Because the virtual disk container is a file on a filesystem that cannot be read while the array under it is failed. You cannot address a .vmdk or .vhdx until the physical array geometry is reconstructed and the host filesystem (VMFS or NTFS/ReFS) is parsed. Array reconstruction is a hard prerequisite for any VM-layer work.
The nesting-doll structure forces the order of operations. The host has no way to read the .vmdk descriptor, the VMFS file descriptor heap, or the NTFS run list for a .vhdx while the block device underneath is incomplete. Tools that operate at the VM layer assume a stable block device beneath them. On a degraded array that assumption is false, and running them can write damage into the only surviving copies of the container headers.
Layer 1: The Physical Array
Several physical members under a Dell PERC, HP Smart Array, or LSI/Broadcom MegaRAID controller, or a Linux mdadm software array
Stripe size, member order, and parity rotation define how the host volume is laid out across the members
When enough members drop, the controller marks the virtual disk failed or offline and presents nothing to the host
This layer must be reconstructed first, virtually, from read-only images of the surviving members
Layer 2: The Virtual Disk Container
The host filesystem (VMFS for VMware, NTFS or ReFS for Hyper-V) sits on the reconstructed volume
VMware stores .vmdk descriptor plus flat-extent files; Hyper-V stores .vhdx base disks and .avhdx differencing chains
The container is located by walking the host filesystem allocation structures, then extracted from the raw image
The guest filesystem inside the container is mounted read-only last, to recover the actual user data
Compound Workflow04/10
What is the Correct Order of Operations for VM-on-RAID Recovery?
The order is fixed: image members, reconstruct the array, extract the container, mount the guest. Imaging and reconstruction are two separate stages. Imaging hardware reads sectors from each member; array-aware software reassembles the geometry from those image files, never from the live members.
Image every surviving member, read-only. Each member is cloned through a write-blocked imager (ddrescue, DeepSpar Disk Imager, PC-3000 Portable III, or PC-3000 Express). The imaging hardware reads and captures sectors; it does not assemble the array. Nothing is ever written back to the original degraded members.
Reconstruct the array geometry virtually, in software. The on-disk controller metadata is parsed from the image files, and stripe size, member order, and parity rotation are reassembled with array-aware forensic software (Data Extractor Express RAID Edition) or with mdadm --assemble --readonly for Linux software arrays, run against the images, never the live members.
Extract the VM container files. The reconstructed host volume is parsed directly from the raw image. For VMware, the VMFS file descriptor heap is scanned for .vmdk descriptors and flat extents. For Hyper-V, the NTFS or ReFS volume is parsed for .vhdx and .avhdx files. Each container is extracted from the reconstructed image.
Mount the guest filesystem read-only. Each extracted virtual disk is mounted read-only and the guest filesystem (NTFS, ext4, XFS) is verified before any data is delivered. No filesystem repair touches the original media at any stage.
Imaging and reconstruction are deliberately named as two distinct stages. The PC-3000 Portable III, PC-3000 Express, and DeepSpar Disk Imager image and read sectors from each member drive. The array geometry is then reconstructed virtually in software against the image files. No hardware imager rebuilds the array; no reconstruction software ever touches the live degraded members.
Rebuild Hazard05/10
Why Should You Not Rebuild the Degraded Array First?
A rebuild on a degraded array pins every surviving member at sustained full-surface read for hours, and on multi-TB members the probability of hitting an unrecoverable read error during that read is meaningful. A URE on a degraded RAID 5 can halt parity recalculation, drop a second member, and crash the array. Image first.
RAID 5 tolerates one failed member by recomputing its contents from distributed parity. To rebuild that member the controller must read every sector of every surviving drive. On modern multi-TB members the probability of encountering an unrecoverable read error across a full-surface read is significant, and the chance rises with array capacity. If the controller hits a URE while the array is already degraded, it can stop recalculating parity for the affected stripe. A legacy or low-end controller treats that as a second member failure and aborts the rebuild; the array crashes. Modern Dell PERC and LSI/Broadcom MegaRAID may puncture the affected stripe and continue, losing only that stripe, but a punctured stripe can land on VMFS metadata or a .vmdk or .vhdx flat extent.
The rebuild read also stresses aging members mechanically. A same-batch survivor that is marginal can fail outright during the sustained read, turning a single-member fault into a double-member fault on a RAID 5 that cannot tolerate it. For irreplaceable, unbacked data on a degraded array we do not gamble on a live rebuild. Rebuilding a degraded array forces parity recalculation across the surviving members, so each member is imaged read-only first and the array is reconstructed against the copies. RAID is fault tolerance against drive failure; it is not a backup, and a failed array with no separate backup is exactly the case this workflow exists for.
Controller Metadata06/10
Do You Need the Original RAID Controller to Rebuild the Array?
No. The structural metadata that defines the array geometry lives on the member drives, not in the controller NVRAM. Dell PERC and LSI/Broadcom MegaRAID write a SNIA DDF variant on the trailing sectors; HP Smart Array writes a proprietary RIS at the start of each drive. We parse that on-disk metadata from the images, so a dead controller does not block recovery.
The myth that you must have the exact original controller card to read a hardware array is outdated. Enterprise controllers persist their array configuration to the member drives so that an array survives a controller swap. That same on-disk metadata is what makes virtual reconstruction possible after the controller dies.
Dell PERC and LSI/Broadcom MegaRAID
These controllers write a SNIA DDF (Disk Data Format) variant on the trailing sectors of each member. The metadata records the RAID level, stripe size, member ordering, and consistency state. We read it from the drive images and reconstruct the geometry with array-aware forensic software, without the original card. PERC foreign-configuration states are read the same way.
HP Smart Array
HP Smart Array does not use DDF. It writes a proprietary RIS (RAID Information Sector) at the start of each drive. The metadata format differs from PERC and MegaRAID, but it is still on the disks, so the Smart Array geometry can be reconstructed from the member images without the original controller.
Linux mdadm software arrays
Software arrays store an mdadm superblock on each member. We read it with mdadm --examine and assemble against the images using mdadm --assemble --readonly, never the live members.
Where the metadata has been overwritten or zeroed (for example a controller firmware flash gone wrong), we fall back to brute-force parameter detection, testing stripe-size permutations and member orderings against known filesystem signatures in the reconstructed image until the VMFS or NTFS layout resolves cleanly.
VMware vs Hyper-V07/10
How Does the VMware Leg Differ from the Hyper-V Leg?
The array-reconstruction stage is identical. The difference is the host filesystem and container format extracted afterward. VMware uses VMFS hosting .vmdk; Hyper-V uses NTFS or ReFS, optionally under a CSV coordination layer, hosting .vhdx and .avhdx. The container internals are detailed on the dedicated VMware ESXi and Hyper-V pages.
Layer
VMware leg
Hyper-V leg
Host filesystem
VMFS5 or VMFS6 clustered filesystem
NTFS or ReFS LUN, optionally under a Cluster Shared Volume layer
Coordination layer
On-disk heartbeat and ATS locks; irrelevant offline
CSV cluster coordination; irrelevant for offline image-first recovery
Container files
.vmdk descriptor plus flat-extent and snapshot deltas
.vhdx base disk plus .avhdx differencing chain
Internal change tracking
Grain directories and grain tables in delta extents
Block Allocation Table and log region in each VHDX
This page owns the compound array-failure case. The deep container internals, VMFS metadata structures, VHDX Block Allocation Table layout, snapshot and checkpoint chain consolidation, and vSAN or Storage Spaces Direct specifics live on the two dedicated pages above. Send a case here when the array under the datastore has failed and must be reconstructed before any of that container work can begin.
Pricing08/10
How is VM-on-RAID Recovery Priced?
Pricing is the aggregate of two named components: a per-member imaging fee based on each drive's condition, plus one array reconstruction fee ($400-$800) covering virtual array reassembly, host filesystem parsing, and VM container extraction. Each member drive is imaged and priced individually. No data recovered means no charge.
Service Tier
Price Range (Per Drive)
Description
Logical / Firmware Imaging
$250-$900
Firmware module damage, SMART threshold failures, or filesystem corruption on individual array members.
Mechanical (Head Swap / Motor)
$1,200-$1,50050% deposit
Donor parts consumed during transplant. SAS drives require SAS-specific donors matched by model, firmware revision, and head count.
Array Reconstruction + VM Extraction
$400-$800per array
Virtual array reassembly, VMFS or NTFS/ReFS parsing, and .vmdk or .vhdx extraction, plus checkpoint or snapshot chain consolidation where applicable.
No Data = No Charge: If we recover nothing from your array, you owe $0. Free evaluation, no diagnostic fee, no obligation.
Published pricing. Per-member imaging tiers come from our standard HDD pricing; the array fee is a single published reconstruction charge. The work is the same regardless of what label an invoice puts on it.
Process09/10
How Do You Send a Failed Array In and What Happens Next?
Power the server down, label each drive by bay, and mail the full member set to our Austin, TX lab. Every member is imaged read-only, the array is reconstructed virtually in software, the host filesystem is parsed, and the VM containers are extracted. No diagnostic fees, no data no fee.
1. Power down and ship the full member set
Stop further writes by powering the host down. Do not trigger a controller rebuild and do not run a filesystem repair against the datastore. Label each drive with its bay position so the original member order is documented, and mail the complete set to our Austin, TX lab. All work is performed in-house at that single location; there are no franchises and no outsourcing.
2. Imaging stage
Each member is imaged through PC-3000 Portable III, PC-3000 Express, or DeepSpar Disk Imager using SAS HBAs for SAS drives or SATA and NVMe adapters as appropriate. The imager reads and captures sectors from each member; for drives with bad sectors we map heads, skip damaged regions on the first passes, and revisit them with aggressive retry parameters afterward. Mechanical members are opened on a 0.02 micron ULPA-filtered clean bench when a head swap is required.
3. Reconstruction stage
The array geometry is reconstructed virtually in software, against the image files, never against the live members. On-disk DDF or RIS metadata is parsed to recover stripe size, member order, and parity rotation, with Data Extractor Express RAID Edition for hardware-controller arrays or mdadm --assemble --readonly and LVM activation for Linux software arrays. The reconstructed host volume is then parsed and the .vmdk or .vhdx containers are extracted and verified by mounting the guest filesystem read-only.
4. Confidentiality and delivery
We do not process regulated healthcare workloads. For standard commercial confidentiality, legal holds, and engineering data we sign an NDA and keep drives under chain-of-custody documentation in the Austin lab for the duration of the case. Recovered data is returned on a customer-provided destination drive or as full VM images. Rossmann Repair Group has performed recovery work in-house since 2008.
Faq10/10
VM-on-RAID Recovery; Common Questions
What makes a VM-on-failed-RAID case different from normal VMDK recovery?
It is two stacked recovery problems instead of one. The .vmdk or .vhdx container is a file living on a host filesystem (VMFS or NTFS), and that filesystem lives on a RAID volume. When the array itself has failed, the host filesystem cannot be read at all, so the virtual disk container cannot be addressed yet. The physical array must be reconstructed at the block level before any VM-layer extraction is possible. A normal VMDK case assumes the underlying volume is already healthy and mountable.
Should I just rebuild the degraded RAID array and let the VMs come back?
No. Triggering a controller rebuild on a degraded array pins every surviving member at sustained full-surface read for many hours. A marginal same-batch survivor can fail mechanically in that window, and on a multi-TB array the probability of hitting an unrecoverable read error during the rebuild read is meaningful. If the controller hits a URE on a degraded RAID 5, it can halt parity recalculation, drop a second member, and crash the array. Image every member read-only first, then reconstruct virtually against the copies.
Do you need the original Dell PERC or HP Smart Array controller to rebuild the array?
No. The structural metadata that defines stripe size, member order, and parity rotation lives on the member drives, not in the controller NVRAM. Dell PERC and LSI/Broadcom MegaRAID write a SNIA DDF variant on the trailing sectors of each member; HP Smart Array writes a proprietary RIS (RAID Information Sector) at the start of each drive. We parse that on-disk metadata from the drive images and reconstruct the array geometry in software, so a dead or missing controller does not block recovery.
Is it safe to run vmkfstools, chkdsk, or a filesystem repair on the corrupted datastore?
No, not on the original media. In-place filesystem repair tools force logical consistency by overwriting metadata, which can destroy the .vmdk or .vhdx container headers before they are ever extracted. If the underlying cause is a degraded array with bad sectors, those tools are operating on top of an unstable block device and the damage compounds. Repair only belongs on a verified copy, after the array is imaged and reconstructed.
How does the recovery differ between a VMware VMFS datastore and a Hyper-V CSV?
The array-reconstruction stage is identical for both. The difference is the host filesystem and container format on top. VMware uses VMFS5 or VMFS6 hosting .vmdk descriptor plus flat-extent files. Hyper-V uses standard NTFS or ReFS LUNs, optionally coordinated by a Cluster Shared Volume layer, hosting .vhdx and .avhdx files. For offline image-first recovery the CSV coordination metadata is irrelevant. The container internals of each format are covered on our VMware ESXi and Hyper-V pages.
My Cluster Shared Volume went offline. Is the CSV coordination layer the problem?
Usually the CSV coordination layer is not where the data loss is. CSV is a cluster coordination layer on top of a standard NTFS or ReFS LUN. When the backing RAID array or SAN LUN drops to a RAW state, every VM on that volume goes offline, but the .vhdx files are still on the physical drives. We image the underlying members, reconstruct the array, parse NTFS or ReFS from the raw image, and extract the .vhdx and .avhdx files directly. The coordination metadata is not needed offline.
Why is a degraded RAID 5 under a datastore considered high-risk during rebuild?
RAID 5 tolerates one failed member by recalculating its data from distributed parity. With a member already missing, a full rebuild must read every sector of every surviving drive to recompute the missing data. On modern multi-TB members the probability of encountering an unrecoverable read error during that full-surface read is significant. A URE on an already-degraded array can stop parity recalculation, the controller may drop a second member, and the array collapses. That is why we image member-by-member before any rebuild rather than gamble on the live array.
Does it matter whether the array is RAID 5, RAID 6, or RAID 10?
The array level changes the geometry we reconstruct and the parity math, not the workflow. RAID 6 carries dual parity (P and Q) and survives two failed members, RAID 10 mirrors then stripes, and RAID 50 or RAID 60 nest parity sets under a stripe. We parse the on-disk controller metadata to determine the exact level, stripe size, member order, and parity rotation, then reconstruct that geometry virtually from the member images before parsing the host filesystem.
The array came back but the VMFS or NTFS volume is corrupt. What now?
If the volume corruption was caused by the array failure (a torn write across a degraded stripe, or an aborted controller rebuild), the safest path is still image-first. We image the members, reconstruct the array virtually, then parse VMFS or NTFS structures directly from the raw image rather than asking the host to mount a damaged volume. Container files are located by following the filesystem allocation structures, even when the host mount fails.
Can you extract a VHDX with a broken checkpoint or .avhdx differencing chain?
Yes. Once the array is reconstructed and the NTFS or ReFS volume is parsed, we locate the base .vhdx and every .avhdx differencing disk. Each .avhdx records changed blocks relative to its parent through its Block Allocation Table. We read the parent locators, order the chain, and consolidate the differencing data into a flat virtual disk at the most recent consistent state. The deeper container internals are detailed on our Hyper-V page.
How is pricing calculated for a VM-on-RAID recovery?
Pricing is the aggregate of two named components: a per-member imaging fee based on each drive's condition, plus one array reconstruction fee ($400-$800) covering virtual array reassembly, host filesystem parsing, and VM container extraction. Each member drive is imaged and priced individually. No data recovered means no charge, and there are no diagnostic fees.
How do I send a multi-drive array in for recovery?
Power the server down to stop further writes, label each drive with its bay position, and mail the full set of members to our Austin, TX lab. All work is performed in-house at that single location. We sign an NDA and keep drives under chain-of-custody documentation throughout. Free evaluation, no data no fee, no diagnostic fee.
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 maintain drive integrity. This approach allows us to serve clients nationwide with consistent technical standards.
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.
Our "No Data, No Charge" policy means we assume the risk of the recovery attempt, not the client.
LR
Technical Oversight
Louis Rossmann
Our engineers review all lab protocols to maintain 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.
“Had a raid 0 array (windows storage pool) (failed 2tb Seagate, and a working 1tb wd blue) recovered last year, it was much cheaper than the $1500 to $3500 Canadian dollars i was quoted by a Canadian data recovery service. the price while expensive was a comparatively reasonable $900USD (about $1100 CAD at the time). they had very good communication with me about the status of my recovery and were extremely professional. the drive they sent back was Very well packaged. I would 100% have a drive recovered by them again if i ever needed to again.”
“HIGHLIGHT & CONCLUSION
******Overall I'm having a good experience with this store because they have great customer services, best third party replacement parts, justify price for those replacement parts, short estimate waiting time to fix the device, 1 year warranty, and good prediction of pricing and the device life conditions whether it can fix it or not.”
“Didn't *fix* my issue but a great experience. Shipped a drive from an old NAS whose board had failed. Rossmann Repair wanted to go straight for data extraction (~$600-900). Did some research on my own and discovered the file table was Linux based and asked if they could take a look. They said that their decision still stands and would only go straight for data recovery.”
“I've been following the YouTube tutorials since my family and I were in India on business. My son spilled Geteraid on my keyboard and my computer wouldn't come on after I opened it and cleaned it, laying it upside down for a week. To make the story short I took my computer to the shop while I'm in New York on business and did charged me $45.00 for a rush assessment.”
