Two or more disks down
RAID 5 with two failures, RAID 6 with three. The array is offline. Do not start rebuild under any circumstances.
Data recovery for RAID and servers
Intervention on complex RAID systems, enterprise servers and critical configurations with data loss or multiple failures.
- Diagnostic in 3–5 business days
- No recovery, no fee
- MRW pickup across Spain
Advanced RAID array reconstruction
RAID systems require complete logical reconstruction: disk order, parity, blocks and internal structure.
One mistake in the process can permanently destroy the data.
RAID types
- RAID 0, 1, 5, 6
- RAID 10
- NAS and servers
- Hybrid configurations
- Virtualised systems
Common scenarios
- Multiple disk failure
- Degraded RAID
- Damaged controller
- Failed rebuild
- Lost configuration
- Inaccessible server data
Recovery process
Request diagnosticSystem diagnostic
RAID identification
Logical reconstruction
Safe imaging
Data extraction
Related services
When you need a lab
Symptoms of an array you should no longer touch
Modern RAIDs are designed to survive one or two disk failures. When the symptoms below appear, what was redundancy becomes a risk: any in-place rebuild attempt can destroy the rest of the array.
Rebuild stalled or failed
Reconstruction stuck at 47% for days. Usually indicates unreadable sectors on another supposedly healthy disk.
Dead controller
PERC, Smart Array or LSI that doesn't power on or doesn't detect the disks. The array is intact but reading is impossible without virtual reconstruction.
Lost configuration
The NAS shows disks as 'uninitialised', the system asks to format, or the array appears as JBOD. The metadata is corrupted.
Anatomy of the array
Stripe, parity, metadata and why we never touch the original
A RAID array is not the sum of its disks: it's a logical map that defines how blocks are distributed among them. That map includes the disk order, stripe size (typically 64 KB, 128 KB, 256 KB), parity rotation (left-symmetric, right-asymmetric, etc.) and the position of metadata on each disk (at the start, at the end, on sector 0, on an LBA reserved by the controller). Without all these exact parameters, the data is there but unreadable — like having all the pages of a book shuffled and unnumbered.
The parity is what allows a RAID 5 to reconstruct the content of a lost disk from the XOR of the rest, and a RAID 6 to survive losing two. But that same parity becomes useless if the surviving disks have marginal sectors: when the rebuild tries to read every block to calculate the new disk's content, a single URE (unrecoverable read error) on another disk can abort the reconstruction and leave the array doubly degraded. It's the classic failure of RAID 5 with large disks.
That's why our first operation is always the same: individual cloning of each disk onto healthy targets, in forced-read mode with error tolerance (ddrescue, deepspar). From the cloned images we reconstruct the array virtually — trying combinations of order, stripe and rotation until the filesystem validates — and extract the data. The original disks are never connected to the original controller, nor allowed to attempt any rebuild.
Before touching the array
Mistakes that destroy recoverable RAIDs
Almost every array that arrives at the lab in an irrecoverable state does so after a well-intentioned previous attempt. These are the most expensive — and the most common.
Launching a rebuild on a degraded array
If another disk has marginal sectors, the rebuild finishes it off. Clone first, rebuild later.
Changing the disk order
Hardware controllers identify disks by bay number. Mixing the order makes the array unrecognisable or, worse, initialises it incorrectly.
Accepting the NAS 'initialise disks' prompt
One way or another, the NAS will lose the array configuration and the data. If it asks to initialise, power off and isolate the disks.
Running fsck or chkdsk on the array
These utilities rewrite filesystem metadata. On a poorly reconstructed array, they can permanently destroy the directory structure.
Replacing the controller with a different one
Each manufacturer has its own metadata format. Connecting PERC disks to LSI or vice-versa can overwrite the headers.
Forcing the array online ignoring warnings
When the controller marks the array as inconsistent, there's a reason. Forcing online without prior diagnostic is the recipe to lose everything.
Full coverage
RAID levels and systems we recover
We work with hardware and software arrays, classic enterprise configurations and home NAS. If your setup isn't listed, write to us: we likely cover it.
RAID 0 / 1 / 10
Stripes, mirrors and combinations. No parity but with full dependency on block order. Virtual reconstruction from cloned images.
RAID 5 / 6
Rotating parity (single and dual). Automatic identification of order, stripe and rotation pattern. Recovery with two missing disks on RAID 6.
RAID 50 / 60
Nested configurations common in enterprise servers. Two-level reconstruction: inner arrays first, outer stripe afterwards.
Synology SHR / SHR-2
Synology proprietary RAID based on mdadm + LVM + Btrfs/ext4. Full support including expansions with disks of different sizes.
QNAP, WD My Cloud, Buffalo
NAS with mdadm+ext4, ZFS or proprietary RAID. Btrfs snapshot export and degraded ZFS pool reconstruction.
Hardware: PERC, Smart Array, LSI
Dell PERC H7xx/H8xx, HP Smart Array P4xx/P8xx, LSI/Broadcom MegaRAID, Adaptec, Areca. Metadata reading without the original controller.
Supported filesystems: NTFS · ext4 · XFS · Btrfs · ZFS · ReFS · HFS+ · APFS · VMFS (VMware)
What we get asked the most about RAID and servers
What if two disks fail simultaneously in a RAID 5?
A RAID 5 tolerates the loss of a single disk. If two go down at once, the array enters offline state and the data is not accessible from the OS. Recovery is possible but requires individual cloning of the surviving disks and virtual array reconstruction outside the original controller — never attempt a physical rebuild, which would destroy remaining data.
Why can a RAID rebuild make things worse?
When a failed disk is replaced and the controller starts rebuild, it reads all the other disks at maximum throughput for hours. If any of them has marginal sectors or was on the verge of failure, that additional load usually finishes it off. That's why, with a degraded RAID, the prudent move is to clone before pressing rebuild.
Do you recover Synology, QNAP, WD My Cloud or Buffalo NAS?
Yes. We work with the main home and semi-pro NAS manufacturers. Synology uses SHR/SHR-2 over Btrfs or ext4, QNAP usually combines mdadm + ext4 or ZFS, WD My Cloud uses proprietary RAID variants. We reconstruct the array virtually without touching the original NAS configuration.
What information do you need to start the diagnostic?
Ideally: RAID level (0, 1, 5, 6, 10, JBOD, SHR), total disk count, controller or NAS make and model, filesystem (ext4, Btrfs, ZFS, NTFS, XFS) and a brief failure history. If you don't know, no problem: part of the diagnostic work is identifying the exact layout from the disks themselves.
Can I keep using the disks while waiting for the shipment?
No. Any attempt to mount the array, launch rebuild or run utilities like fsck/chkdsk on a degraded RAID can overwrite metadata critical for reconstruction. The rule: power off the system, don't touch the disks, and ship them in numbered order (label each bay before removing them).
How long does it take to recover a RAID with 4 or 6 disks?
Complete technical diagnostic in 3–5 business days after receipt. Individual disk cloning can take 2-5 days depending on capacity and physical state of each one. Virtual array reconstruction and data extraction usually completes in another 3-7 days. In total, a typical enterprise RAID recovery is delivered in 7-15 calendar days.
Do you work with hardware RAID (Dell PERC, HP Smart Array, LSI)?
Yes. We handle the metadata formats of the main hardware controllers: Dell PERC H7xx/H8xx, HP Smart Array, LSI/Broadcom MegaRAID, Adaptec, Areca. Recovery is always done on cloned images, never on original disks and never connected to the original controller.
Do you sign NDAs for companies?
Yes. For enterprise clients we sign a specific NDA before any intervention and, optionally, a framework contract with confidentiality clauses and delivery deadlines. The whole recovery process happens at our facilities, the disks don't leave the lab, and data is delivered on AES-256 encrypted media.
RAID
Recover your RAID system risk-free
Specialised intervention in critical environments. Free evaluation.