Taking work now — the first look is freeNAS drives posted in from anywhere in the UK, or handed in at ten drop-off pointsQuicker still, give us a ring:0800 6890668
NDRNAS Data Recovery 0800 6890668 Price my job
NDR / Every kind of NAS / TrueNAS, Unraid, OMV

TrueNAS · FreeNAS · Unraid · OpenMediaVault · XigmaNAS · Rockstor

TrueNAS, Unraid and the home-built NAS. The drives are yours, and so, usually, are the commands typed at two in the morning.

A home-built NAS is a PC or a MicroServer running TrueNAS, Unraid, OpenMediaVault or one of their relatives, and it fails in the same ways a commercial unit does plus the ones that only a shell prompt makes possible. A ZFS pool that would not import gets imported with -F; an Unraid array with a failed disk gets its parity rebuilt with the wrong disk assigned; an mdadm array under OMV gets --create run over it. The good news is that ZFS remembers everything, Unraid keeps each disk's file system on that disk alone, and mdadm's superblocks survive most of what is done to them. Every disk is imaged and the pool or array is brought up from the images, read-only. A set of two or more disks is £500 + VAT upwards after the free look, fixed in writing, 5–10 days at the bench.

Free first lookOne fixed figure in writingNo data, no bill on most jobsReturn postage paid

Rather talk it through? An engineer answers the bench line
0800 6890668

Power it down. Label each drive with its bay number. Do not rebuild, repair, initialise, reinstall or reset. A rebuild reads every sector of every surviving drive, and on a set with a second weak member it finishes what the first failure began. Nothing on the drives gets worse while the unit is off.

Home-built NAS symptoms, and what each means.

Not listed? Describe it on the form →
zpool import: one or more devices is currently unavailableA member missing. Do not force it.Do not delay
Pool FAULTED, or corrupted data reported on importMetadata damage or too many members lost. Power down.Do not delay
Unraid: unmountable, no file systemThe disk's own file system is damaged. Do not format.Do not delay
Unraid parity rebuild ran with a failed disk assignedParity was rebuilt from bad data. Stop; the disk's own file system may still be there.Do not delay
OMV: mdadm array inactive after a rebootA superblock problem or a dropped member. Do not --create.Do not delay
The HBA or controller dropped several disks at onceUsually cabling or power, not the disks. The pool is fine on the bench.Everyday job
Packing it and posting it: power the unit down, write the bay number on each drive with a marker before it comes out, and send every drive from the set, including any SSD cache. Each drive travels in an anti-static bag inside its own padding, in a box with nothing able to move; the unit itself comes too if it holds an encryption key or a proprietary layout, and its power supply with it. Insure the parcel for what the files are worth rather than the price of the drives, and use a tracked service. The posting address is not printed anywhere on this site; it arrives by email in reply to the form, with a booking sheet to print; the sheet inside the parcel is what matches it to your enquiry when it is opened. Or hand the sealed parcel in at the nearest of ten drop-off points, your name on the outside and the sheet inside; say where you are on the form and it comes by email. We pay the postage home either way. The whole of it is written up on the guide to packing and posting.

How it is laid out, and what fails.

ZFSA copy-on-write file system with checksums on everything and a history of transaction groups. A pool that will not import can usually be imported read-only at an earlier transaction from the disk images; a pool that was force-imported and written to has less history to go back to.
UnraidNo striping: each data disk carries its own XFS, Btrfs or ZFS file system, and one or two parity disks protect against a failure. A single disk can be read alone; a parity rebuild with the wrong disk assigned, or against a second weak disk, is the usual loss.
OpenMediaVault, XigmaNAS, Rockstormdadm with ext4 or XFS on OMV; ZFS or UFS on XigmaNAS; Btrfs on Rockstor. The same superblocks and the same rules as the commercial units.
The hardwareConsumer HBAs, SATA controllers and power supplies that drop several disks at once when they fail. A pool that lost four disks in a second has usually lost a cable, and the disks are fine.

What the shell says, and what it means.

Describe yours to us →
What you see The usual reason for it Where that leaves you
cannot import 'tank': one or more devices is currently unavailableA member missing or a label unreadableDo not use -f or -F; images first
cannot import 'tank': I/O error / corrupted dataMetadata damageRead-only import at an earlier txg from the images
pool state FAULTED / UNAVAILToo many members lostEach member imaged; pool imported from images
Unraid: Unmountable: No file systemThe disk's file system damagedImaged; XFS or Btrfs repaired on the image
mdadm: md0 inactive / assemble failedSuperblock or member troubleSuperblocks read from the images; assembled in software
Several disks dropped at onceCable, HBA or PSUDisks read on the bench; pool assembled

From the box arriving to your files going back.

Work we have closed →
01

Logged the day it lands, and the first look costs nothing Free

A case number goes on the parcel and a number on every drive the day it is opened, and an engineer settles what has actually happened before anything spins. The unit is examined on its own; each drive is assessed on our own equipment, never in a NAS that will try to rebuild. Back to you come two things together: a straight note of what is liftable and what is not, plus one figure, fixed and written down. Accept it, or decline and owe us nothing.

Nothing to pay for lookingA single figure, put in writingNo rebuilds, no repairs, no resets
02

The unit, and the drives, apart

The box and the disks are two different jobs. The unit is tested separately, because a dead power supply, a failed board or a bricked boot flash leaves the drives untouched more often than not. Each drive is then read on the bench: the ones that answer at full speed, and the weak or failed ones in clean air where they need head work. On units that hold an encryption key or a layout of their own, the unit is part of the data and is kept with it.

Unit and disks assessed separatelyFailing members to the clean bench
03

Every member imaged, once

ZFS pools are imported read-only from the images, at the latest transaction group that is consistent, and rolled back further where the current one is not; Unraid data disks are mounted from their own images one by one, with parity used to reconstruct a missing disk; mdadm arrays are assembled from the superblocks on the images and the file system repaired on the virtual volume.

Every drive, including the cacheWeak areas last
04

The set put back together, from the images

Order, chunk size, parity rotation and the reshape point are read from the drives' own metadata and the array is reassembled in software: mdadm and LVM under SHR, X-RAID and QTS pools; a ZFS pool imported read-only; Drobo's BeyondRAID zones reconstructed. The file system, Btrfs, ext4, XFS or ZFS, is repaired on the virtual volume, and encrypted volumes are unlocked there with the key you supply. Never on the originals.

Rebuilt in software, from imagesThe file system repaired on the virtual volume
05

You see the file list before you pay

What was recovered is listed for you first, and only then does a bill exist. Approve the list and it is invoiced; turn it down and it is not — and where nothing has come back, most jobs carry no charge at all. Recovered data travels home on fresh media bought in for your job, with the postage at our end. Your case is not closed until you have opened the files on a machine of your own.

No charge until you accept the figureFresh media, supplied with the job5–10 days at the bench

What arrives most often

  • Never force an import. zpool import -F discards transactions to get the pool to mount, and -X more; every one discarded is history the bench could have used.
  • Do not run a scrub, a rebuild or zpool clear on a pool with a suspect member. All three write.
  • Unraid: check the assignments before a rebuild, and never rebuild against a disk that is throwing errors. If a rebuild already ran wrong, stop: the data disks' own file systems are often still readable.
  • Tell us what was typed. The command history is part of the case, and honesty about a forced import or a --create shapes the plan.

One job, followed all the way through.

UK · NDR-2026-0536JOB LOGGED ✓

A TrueNAS SCALE box with six drives in RAIDZ2 that would not import after a power cut, and an import -F that made it worse

Two drives had dropped in the power cut and the owner had forced the import, which discarded the last transactions. All six drives were imaged on the bench and the pool imported read-only from the images at the last transaction group before the force. The datasets came back complete, including the one the force had lost.

100% of the datasets recovered7 days here, and back by post
Illustrative example — replace with a genuine case

What helps, and what harms.

Do this much first

  • Power it down and stop any scrub or rebuild
  • Note every disk's assignment, slot and serial
  • Send every disk, and the boot device if you can
  • Send the exact commands and messages, copied out

What sets us back

  • zpool import -F or -X, zpool clear, or a scrub
  • Formatting an unmountable Unraid disk
  • Rebuilding parity with a disk showing errors
  • mdadm --create on an array that will not assemble

Questions answered before you commit.

My ZFS pool will not import. Is the data gone?

Rarely. ZFS keeps a history of transaction groups and checksums everything, and a pool imported read-only from the disk images at an earlier transaction usually comes back whole. What loses data is forcing the import on the originals.

Can you read an Unraid disk on its own?

Yes. Unraid keeps each data disk's file system on that disk alone, so a single disk is imaged and mounted, and parity is used only to reconstruct a missing one.

I ran mdadm --create over my OMV array. Is it gone?

Not necessarily. --create writes new superblocks but not new data; if the geometry can be worked out, the old array is reassembled from the images. Tell us exactly what was typed.

What does it cost?

A set of two or more disks is £500 + VAT upwards after the free look; eight disks or more from £1,250 + VAT.

How long does it take?

5–10 days at the bench for most pools.

Begin here if yours is doing the same thing.

ZFS pool will not import →TrueNAS / FreeNAS →Unraid →OpenMediaVault →Four-bay RAID 5 and 6 →

Nothing gets worse while it is powered down.

Looking at it is free. Back comes a list of what opened and what did not, together with a single price to finish, set down in writing while you are still free to say no. On most jobs an invoice only follows the data. Until that list reaches you, leave the unit off and the drives in their bays.

0800 6890668

Price my jobPacking and posting