Taking work now — the first look is freeSpinning disks in a machine Quicker still, give us a ring:0203 0868633
ADR Advanced Data Recovery 0203 0868633 Price my job
ADR / Media and machines / RAID 1 mirror sets

Mirror sets · two disks, one volume

RAID 1 data recovery, London. A mirror is two disks that have drifted apart. Post both; the volume comes from the better of each.

We charge from £500 + VAT for RAID, NAS and server work, and the diagnosis we perform to settle the cost is free. In theory, having a mirror will put each block on both drives, therefore either drive could contain the entire volume. In practice, the sets we receive are the ones that fall outside of this theoretical coverage: a pair of drives from the same carton, ageing at the same rate; a controller corrupting both sides identically; a re-sync run in the wrong direction; and a box that lost one of its drives in March and has been operating solely on the remaining drive since. We clone each member individually, as read-only. These clones are then compared, block for block, and the volume is reconstructed using only what each side can still support, with the preference given to the newer read when there is a difference. Sets are sent to us by post from Islington, Barnet, Lewisham and Bromley, and your own disks go home with nothing written to them. We do not have a counter in London. However, disks may be taken directly to our Guildford intake lab, Monday to Friday, 9am to 5:30pm, and dropped off with no appointment needed.

Only pay if we recover your data, on most jobs A free look first, then one figure in writing Media posted in from Croydon, Ealing and Camden

Put it to an engineer — the first look costs nothing
0203 0868633

RAID 1: what the symptom usually means.

Different fault? Try the finder →
What is going onThe usual reason for itWhere that leaves you
The NAS reports that the volume is degradedOne member has gone. The disk still in the bay is holding the entire volume by itself.Copy off what you can, first get a quote, then send both
Both disks have slowed down, and both were put in at the same timeMirrored members clock up the same hours, so wear tends to arrive on both at once.Cut power to the box now.
A new disk was put in, and the side that read went empty.The set was re-synced backwards, so the bad disk was copied onto the healthy one.Stop now, first get a quote, then post both disks.
The same folder is missing from both sides of the mirror.All writes hit both sides at the same instant, bad ones included.Refuse the re-sync
The amber light was not noticed until this week.The mirror has operated with only one disk ever since, with nothing standing behind it.First get a quote, then post both; do not just send the failed one.
Windows labels the mirror as Failed Redundancy.A member has been removed by the set, and quite often neither drive is at fault.Leave it alone: no reactivate, no import.
Packing it and posting it: movement is what finishes off a damaged drive, so pack your unit into a solidly constructed container and fill any empty space with padding material. Get a quote first, by calling us or using the form, and once you receive your quote send your unit tracked and insured to our Guildford intake lab, or drop it off there yourself, Monday to Friday, 9am to 5:30pm (no appointment needed). We pay for the trip home. Would you like your packing materials reviewed prior to taping up your box? Please call first. All of this information is detailed within our guide to packing and posting.

One failure is all a mirror covers. Here is the rest.

Two-bay NAS boxes running as mirrorsA Synology, a QNAP or a bare two-bay enclosure, set up on the day using the safer of the two options. Underneath it is Linux software RAID, which records the mirror on the drives, not in the chassis, so it is safe to leave the box wherever it is: send us the drives, each one labelled according to its bay. Get a quote first, either via phone or with the form; send the whole NAS if you would prefer not to take the top off yourself.
Boot pairs and controller mirrorsThe boot pair under a small server, mirrored by a hardware card or by the Intel RST built into its board. In both cases a record of the set goes on the drives themselves, and it reads back out of clones without the card and without the machine that held them.
Storage Spaces, mdadm and ZFSA mirrored dynamic volume or a Storage Spaces mirror on Windows; an mdadm pair under Linux; two drives running as a ZFS or btrfs mirror in a NAS. Each creates its own layout on the members, each assembles above clones, and each has its own rule for determining which member to believe (that being the very question when one fails).
Why rebuilding can worsen itParity allows a rebuild to calculate the absent drive. A mirror calculates nothing: one member is simply overlaid on the other, whichever way the card decides. Choose wrong and your only sound copy is lost by teatime. On our bench, the same work is done on clones, where taking a wrong turn will cost an afternoon.

From the box arriving to your files going back.

01

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

As soon as your parcel arrives here, an engineer assigns a case number that same day, prior to determining what has really failed, which is the first thing done and costs you nothing. In addition to a note of what can and cannot be recovered from your drive, you will receive at the same time the fixed, written price for restoring what can be recovered. You can accept this quote, or decline it, which will result in no further obligation on your part and nothing owed to us.

Nothing to pay for lookingA single figure, put in writingNothing owed at this stage
02

Each disk cloned on its own

Each member sits behind a write blocker and is copied end to end, and no file is opened until that is finished. The member that never failed receives the same care as the failed member, because on a mirror half of the data sent home comes off it. Ground reading poorly is saved until last and processed in short passes. Your own drives return home with nothing written to them.

Your disks are read, never writtenEach member read by itself
03

The pair of copies compared

When members disagree, something must decide which one to trust. Each member records the date of its last write in its own metadata; where that cannot be settled with the metadata, the file systems on the clones are used. Newer beats older and readable beats unreadable, and all such choices are written down for you instead of being assumed.

The newer side establishedWeighed side by side, not assumed
04

The volume rebuilt above the clones

With the choices made, the volume is reconstructed using the copies, and the file system is mended on those copies and not on the drives you sent. Files are then opened rather than counted: accounts, shared folders, databases, photographs. A filename on a listing does not prove anything. Any file that comes back damaged is recorded as damaged.

Files opened, never merely countedDamage recorded file by file
05

You see the file list before you pay

You will see what has been recovered as a list first, after which a bill exists. Accepting the list means that a bill will be issued. Rejecting the list means that a bill will not be issued, and in most cases you only pay if we recover your data. The recovered data travels from here back to you via new media purchased specifically for your project, with the cost of postage paid by us. Your case is not resolved (i.e., "closed") until you personally view the files on a computer of your own.

No charge until you accept the figureFresh media, supplied with the jobThe post home is ours

What arrives most often

  • Mirrors don't back things up: they duplicate each write onto both disks at the exact same moment, so any deletion, corruption or ransomware attack is copied onto both just as faithfully. The single event a mirror protects against is when one disk fails. This does give you protection, but that is exactly all it offers.
  • Two disks purchased as a pair usually fail as a pair: they were probably sourced from the same batch, placed on the same shelf, put into the same cabinet, and ran for approximately the same amount of time. In many cases, one disk fails and the second follows within weeks. Therefore, owning a degraded mirror does little to extend your recovery window, and the disk still in the bay need not be the better of the two.
  • The direction of a re-sync determines everything: one disk is laid over the top of the other, and which disk is laid over which is determined by the rules of the controller. Most of the bad jobs we see arrive because a failing disk was copied onto a good one, or a stale disk onto a current one. If your box offers to rebuild, decline and call us before doing anything further.
  • Send us the disk the box refuses: get a quote first, then include it. Frequently the refused disk contains the newer data, and frequently that disk will still clone. Hold it back and half of the job will be lost before it even starts; sometimes all of it will be.

What cannot be done: storage is the whole of our business. Here we deal specifically with mirrors (two disks in a network box, two in a desktop enclosure, two on a hardware card, two on an Intel RST board, or a mirrored volume in Windows, an mdadm or ZFS configuration) arriving degraded, overwritten, or re-synced incorrectly. When both sides are read, the volume is rebuilt above the clones, and your folders should appear as they did originally. If the same area has failed on both disks, it is impossible to recreate those blocks: some files will return with gaps (holes) in them, and each of those files will be named in the recovery report. Nor does anything that has been written over come back. Encryption requires its key, and only you have it. No phones or tablets. The price starts at £500 + VAT. Once we complete your free diagnosis, we fix the price for you on paper. On most jobs you only pay if we recover your data.

One job, followed all the way through.

LDN · ADR-2026-3396JOB LOGGED ✓

A two-bay unit that had been running on a single disk since spring

An engineering firm in Ealing contacted us when their office box would no longer present its data volume. Behind a door nobody opens, one drive in the box had dropped out several months previously; although an amber light indicated that something was wrong, the remaining drive continued to support the volume by itself, and it too had begun exhibiting similar symptoms. Each drive was independently imaged; the weaker drive required two nights of short reads. Any data that the failing disk would not relinquish was extracted from its older partner, and any data that could not be obtained from the older disk was retrieved from the newer one instead. Twenty years of drawings and the job ledger were opened here prior to sending the package back to the firm. Three days door-to-door.

The pair of members cloned separately3 days here, and back to you

What helps, and what harms.

Do this much first

  • Pull the power cord and leave the box off
  • Get a quote first, then post every member (yes, the failed one too)
  • Mark each disk with its bay number before removing it
  • Tell us whether a rebuild or re-sync has already run

What sets us back

  • Allowing syncing onto a replacement disk
  • Reactivating a Windows mirror that has been marked as Failed
  • Pointing repair software at either member
  • Posting only one member and keeping the other at home

Questions answered before you commit.

One disk still runs. Why do you want the other as well?

Because you now have two different versions of the same volume. Blocks missing from one member may simply appear on the other. Additionally, one member may be weeks out of date, because it fell out of sync long before anyone glanced at the front of the box. Given that you now have two cloned versions of your volume on a bench, we can draw each block from whichever disk still reads it, dated as you would prefer (which no striped array can do). So get a quote first, by phone or with the form, then send the pair, mark the bays and include the disk that your box refuses to recognise. Post them as tracked and insured parcels or drop them off in person at our Guildford intake lab, Monday to Friday, 9am to 5:30pm (no appointment needed).

The box offers to rebuild onto a replacement. Do I say yes?

No. And this is the most damaging decision possible on this page. A rebuild places one member on top of the other. How the controller chooses which member goes on top depends on its own rules. If the member currently in the bay is the failing member, or simply the stale member, it is your good side that disappears beneath. After that point, there is no longer any secondary version anywhere. Turn off the box, keep the disks in their original bay order and get clones made first. Pressing anything further cannot undo a clone.

A folder I deleted is gone from both members. Is a mirror not the same as a backup?

No. And expecting one to act like a backup is the single most common misconception bringing jobs to this bench. Both members receive each write simultaneously: delete something, save something corrupt or run some ransomware, and both copies carry it. The single event a mirror provides protection against is one disk going bad. As long as data has not yet been overwritten, it remains recoverable, which is why turning off the box that day (rather than waiting until Saturday) is worth doing.

What has to be sent, and what is the price?

£500 + VAT marks where RAID, NAS and server work begins. Diagnostics prior to that point are free, and following diagnosis we will write down and agree upon a fixed price with you before anything chargeable occurs. Obtain a quote prior to sending, by phone or through our quote request form, then send every member with its bay number affixed to it (additionally include the disk that your controller refuses), and tell us about any actions taken thus far. Unwilling to open the chassis? You can send the network box whole. Individual disks pulled from a server chassis or a desktop enclosure travel bare in antistatic bags. There is no collection service provided and we have no counter in London, therefore please use an insured and tracked parcel service to send them directly to our Guildford intake lab (the address is located on our contact page). Drop-offs are welcome there Monday to Friday, 9am to 5:30pm (no appointment needed).

Begin here if yours is doing the same thing.

Servers that refuse to come up → Toshiba laptop drives → RAID and server jobs → Every device we take →

Nothing gets worse while the power is off.

It doesn't cost you anything for us to look at it. All we do is give you a breakdown of what opened and what did not, plus a single fixed price to complete, written down before you agree to let us continue. On most jobs, you only pay if we recover your data. Please don't turn on the drive until you get that breakdown.

0203 0868633

Get it assessed Sending it to Guildford