Two discs that had been working together and wore out together. Resyncing the two discs to each other, but copying them back in the wrong direction. A box that failed while both members inside it were perfectly healthy. None of this is a dead end. The two halves are separately imaged, then judged on what they actually hold rather than on a status flag, and your files will be recovered from whichever proves to be the stronger.
The mirror is quoted, and never guessed at. There's no cost for diagnosis, and the written figure comes after it: from £500 + VAT, charged by disc, and on logical work, in most cases you only pay if we recover your data.
The mirror makes one commitment and meets it well: when a single disc fails, the volume carries on. All of the situations listed below get around that commitment rather than going through it, which is why they end up in a padded box headed for Guildford.
Two discs ordered together, started up on the same day and used identically for the entire time don't politely quit years apart. The gap typically amounts to weeks, and whatever wore the first one out has been wearing down the other all along.
In a dual bay NAS system or in a mirrored desktop system, the first item to fail is usually the controller or the bridge before either of the members. Both discs are perfectly fine, but now they're sealed within an enclosure that can't communicate with anything, so each disc must be read independently.
If you insert the wrong disc, or leave the enclosure alone to solve the problem by itself, the empty or out-of-date member will be copied directly over the current one. The mirror behaves exactly as mirrors do, at full speed, but in the wrong direction.
If the pair ran degraded at different times, each drive now contains a differing version of the same folders. When merged carelessly, these versions will spoil each other. If copied apart, each is free to give up whatever only it still holds.
A deletion, a write that goes wrong, a bad update, an encryption run: mirroring is designed to duplicate each write the instant it happens, so all of these reach both drives at the same time, and neither disc is spared any of it.
When a NAS firmware update fails partway, or when an operating system eats its own boot volume, you have a dead box containing two healthy discs. The way out is to make a copy of each disc, then raise the volume using hardware that works.
What does mirroring really promise? Two discs hold an exact duplicate of each other's data, byte for byte, in real time, as every write is copied to both of the discs before your operating system is told the write was successful. Not one part of this process examines or evaluates the writes. Emptying a folder results in a write; encrypting a file results in a write; saving a mangled copy over a good one results in a write. All of these commands will be carried out faithfully and simultaneously on each member, and that is exactly what a mirror is for and therefore exactly why it protects you from so little.
Put the two ideas side by side and the confusion clears up. A backup is a copy of how things stood at some point in the past, and it is kept apart from the original. A mirror is a live duplicate that sits in the same chassis, on the same power supply, behind the same controller. One of them lets you go back to Tuesday. The other lets you keep trading through a dead disc, which is worth having, but it is not the same service. A deletion, a corrupt update, an encryption run or a lightning strike on the mains: none of those is answered by the mirror. It is also worth adding that nothing on this site is a backup product. There are no contracts and nothing to subscribe to. This is a bench that gets data back, and it will happily tell you where the copies ought to have been living instead.
Each of the members of the mirror holds a small status record. This record includes an event counter that ticks with each event, a timestamp and a flag indicating if this disc is currently in step. When the two are assembled, their records are compared and the higher counter is considered to be authoritative. This design works well, and it explains most instances of resynchronisation failure. If you remove a disc for a couple of weeks and then return it, its counter will genuinely be behind the other's, so the enclosure overwrites it, which is the correct action. However, bring a mirror back online after the controller has failed and those records could be missing, damaged or misread, and the same logic will reach the wrong conclusion with equal confidence.
Nothing in the recovery depends on that record. The two members are copied first. Then, based on the content as opposed to the status flag, the better source is chosen: which one has a coherent file system, which one contains the latest versions of documents whose dates you recognise, and which disc shows the tell-tale signs of being overwritten. A counter read will take about a second and may be wrong. Disc reads take longer, and it's a lot harder for them to mislead anyone.
Nearly all of the pairs that arrive here came out of a two-bay Synology, QNAP or Netgear box, or a small server under a desk: architects and surveyors around Wokingham and Windsor, letting agents and practices in Maidenhead and Ascot, engineering firms near Camberley and Sandhurst, and studios and agencies posting in from the London districts. Firstly get a quote over the phone or complete the free online diagnostic. Then package both discs, labelled by bay, into one parcel to Guildford Data Recovery, Building 2, Ground Floor, Guildford Business Park, Guildford GU2 8XH, tracked and insured (if the discs cannot be removed from their housing, send the entire box). Or drop the discs off at the Guildford lab, Monday to Friday, 9am to 5:30pm, and no appointment is required. The wider picture is on RAID recovery and NAS recovery, the whole county is covered from data recovery Berkshire, and every band is published under data recovery cost.
A mirror can serve a read from either disc, which may appear harmless but can mask a slow problem. Over time sectors degrade. An enclosure with no scrubbing routine has no reason to touch a rarely used area for months, so a member can be quietly failing while the volume reports itself to be perfectly healthy. The issues that arise when symptoms do surface are peculiar rather than dramatic: a document that opened on Monday and refused to open on Thursday; a check that passed and later failed; application software complaining about the same data it previously wrote itself. If the above describes the pattern that led you to this page, both discs are of greater importance than usual, because the intact version of any given file may survive on only one of them.
When the box is opened, the pair is immediately split up so the two can be recovered independently, as two separate jobs. Each member goes onto a hardware imager, and any disc with a physical fault is first stabilised on the repair bench before that starts. Next, the two copies are compared with one another; the copy that holds more of your data, and the more recent versions of it, serves as the baseline for the rebuild, and the missing pieces are then filled in from the second copy. At no point during this process is anything at all written back to either of the originals.
Synology puts its own volume manager on top of the normal Linux setup, as well as a modern file system above that. QNAP does likewise but uses other names. Netgear's X-RAID puts in expansion logic all of its own. They are all readable, and none of them are readable if you just pop a member into your Windows machine and hope. For you the practical result is minimal. Get a quote first, then send both discs instead of one (or the entire unit when you cannot remove the discs). Note which bay each disc came from, and say what make and model the unit was.
The first is to stop as soon as you've noticed. A backwards resync takes a little more with each write it completes, therefore the minute from when you notice until you pull the plug is truly the most valuable of all in the job. The second is to leave the discs alone. Using a desktop computer to test each disc in turn to see which one works will achieve nothing useful: at best you'll learn what the images were going to tell you regardless, and at worst Windows will offer to initialise the disc, and someone will agree. Initialise is the one word on this page that turns a routine job into an awkward one.
Both halves are copied apart, the better one is raised, and the weaker one fills the gaps. Diagnosis is free.
Hardly anything walks in here; it arrives in a padded box. Once you have a quote from us over the phone (or from our free online diagnostic), the least stressful option for storage that has already given up is tracked, insured post, and a parcel handed over at a Bracknell post office before the last collection usually reaches Guildford the following working day.
Is the hard drive still bolted into a machine, whether that is a laptop, a tower, an iMac, a MacBook, a rack server or a DVR stored under the till? Get a quote first, then pull the drive out of the machine and send only the bare drive (never the entire machine): from a server the disks come out labelled by bay, and from a DVR you just send the disk. Stripping hardware is not something our lab does, though any repair shop on your high street can do it in about ten minutes. The one case with no way round it is memory chips soldered flat onto the mainboard, which is how T2 and Apple Silicon Macs and certain ultrabooks are built, and that storage is not taken on. Call us first if you're not sure which kind you have. Where the storage cannot be unbolted, there is no parcel to make up.
↓ Print the shipping & booking-in form (PDF)
With your quote in hand, the name on the parcel wants to be Guildford Data Recovery. Driving it over from Bracknell takes roughly forty minutes along the A322 followed by the A3, and you do not need an appointment; posting it costs you a stamp and a day. Either way, a message goes out to you as soon as the package has been logged onto our system, and two working days after that the diagnostic is finished.
Unsure which items should go in the box? Call 0800 689 0668 whilst the box is still open, or work through the free online diagnostic and let it guide you.