Redundancy hides the first failure, which is why most arrays reach us having quietly lost more than one member. Every disk is imaged read-only, the geometry is derived from the data rather than trusted from a controller that has already failed, and the array is rebuilt virtually — so nothing we do can make the originals worse.
$ bdr diagnose /dev/raid → Array: RAID 5 · 6 × 4 TB · 20 TB volume → Status: OFFLINE — 2 disks failed, rebuild failed → Client: confidential · Oxford OX2 $ bdr engineer-working → Member disks: all 6 imaged read-only → Parameters: order + stripe + parity solved → Array: rebuilt virtually from images $ bdr verify → ✓ databases — 412 GB → ✓ shares + VMs — 17.8 TB → ✓ array recovered — data back
A rebuild writes to the member disks, and where it cannot read parity cleanly it writes wrong data. An array that would have recovered fully can be reduced to fragments by one rebuild started with good intentions. Power it down and preserve bay order.
Almost never the way the documentation implies — redundancy conceals the first failure, so most arrays arrive having lost more than one.
The controller is the one thing that has already demonstrated it cannot be relied on, so nothing it says is taken at face value.
Every member is imaged read-only first, including any disk already marked failed — an ejected member frequently still holds readable data and can be the difference between partial and full recovery. Stripe size, disk order, parity rotation and data offset are then derived from the data itself, with candidate configurations tested until reassembly produces coherent file-system structures rather than noise.
The array is assembled virtually from the images and the file system rebuilt from that. Where a stripe has an unreadable sector on one member, parity from the remainder fills the gap; only stripes with two unreadable members in the same place cannot be resolved. Nothing is written to any original disk at any point. Guides: RAID 1 data recovery and RAID 0 data recovery.
The arithmetic differs by level; the method does not.
Including JBOD, spanned volumes and vendor-specific variants such as Synology SHR and Drobo BeyondRAID.
Dell PERC, HP Smart Array, LSI and Broadcom, Adaptec, IBM ServeRAID and the rest — including cards whose configuration has been lost entirely.
Linux mdadm, Windows dynamic disks and Storage Spaces, ZFS and BSD arrays.
From two-disk mirrors to large enterprise sets. More members means more images and more analysis, which is what the pricing reflects.
Arrays where nobody now knows the level or the order — that is precisely what deriving the geometry is for.
Priced by the work rather than by capacity.
RAID, NAS and server recovery starts from £500 +VAT, confirmed after a free 48-hour diagnostic. Where members need physical drive-level work there is a 50% deposit, with the balance payable only on a successful recovery.
Send every disk, including any already marked failed, labelled with its bay number — and tell us the controller model, the level if known, and crucially what has already been attempted. A rebuild that was started and abandoned changes the approach entirely. Full write-ups: an eight-disk RAID 6 a disk too far, a RAID 0 stripe undone by one disk, a RAID 1 mirror worn thin on both sides, a RAID card that lost track of its array and twelve disks initialised by accident.
Send the array in for its free diagnostic with the RAID level, disk count and controller; an engineer assesses it and confirms the exact quote in writing before any work starts.
Getting your data back starts with getting the array to us — all its disks, labelled in order, or the whole server. Pack it safely, enclose your contact details, and once we've run the free diagnostic we confirm your exact quote in writing before any work begins.
Posting it? A tracked, insured service is what we’d recommend. Rather drop it in? You’re welcome Monday to Friday, 9am to 5:30pm — just package the device up as above first.
Need a scoped quote first? Describe the array, RAID level and fault on the form and an engineer will assess it and reply with a tailored quote.
We’ll be in touch shortly. If it’s urgent, call 01865 593000.
RAID array recovery here covers every common level, and two deserve their own sentence. RAID 0 stripes data across drives with no redundancy at all — one member down takes the whole array with it — yet it recovers well on the bench: every member (including the failed one) is imaged, and the stripe set is reassembled virtually from the copies. RAID 5 survives a single failure but hides its real danger in the rebuild, where a second tired drive gives out under load; a degraded RAID 5 that matters should be powered down and imaged, never rebuilt in place. RAID 6 and RAID 10 follow the same discipline: members imaged first, array logic worked on copies.
The questions we’re asked most about recovering a RAID array.
Often, yes. It depends whether the second disk failed completely or simply dropped out — an ejected member is frequently still largely readable. Both disks come in, every member is imaged, and the array is reconstructed from the copies rather than the hardware.
Not if the data matters. A rebuild writes to the members and, where parity cannot be read cleanly, writes incorrect data. It is the commonest way a recoverable array becomes an unrecoverable one. Power down and send the disks as they are.
Yes, including any already marked failed. Every level except RAID 1 requires the full set to reconstruct the volume, and even an ejected member usually contributes readable data. Label them by bay before removing them.
That is a normal starting point and not a problem. Stripe size, member order, parity rotation and offset are all derived by analysing the disks themselves — the controller’s own metadata is treated as a hint rather than a fact.
Yes. Both are proprietary layouts that have to be derived from images rather than read off the appliance, which is exactly the approach used for any array whose controller cannot be trusted.
From £500 plus VAT, fixed in a written quote after a free 48-hour diagnostic. Where members need physical drive-level work there is a 50% deposit, with the balance due only on a successful recovery.
Free to diagnose, priced on a clear tier from £800 for multi-disk arrays, and no fix no fee on the majority of jobs — every level and controller recovered, NAS through to server. Get your recovery moving today.