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MHDR / Specialist cases / iMac Fusion Drive recovery

Specialist · iMac Fusion Drive recovery

iMac Fusion Drive recovery, Maidenhead. One volume, two drives, and the noisy half decides the job.

People who own an Apple Fusion iMac contact us from Maidenhead and its surrounding areas, describing the problem as follows: the computer slows over time during a period of months, after this a grinding noise is heard coming from inside the rear of the machine. Apple connects a smaller solid-state drive (SSD) with a 3.5-inch mechanical hard-drive and combines both into one "volume", therefore when the mechanical half of the unit fails, it takes the entire volume down with it. On top of this, the display is sealed in, and newer models also include encryption stored within the controller. Newer model T2/Apple-silicon iMacs have the storage soldered onto the motherboard and are not taken on. If you are unsure what type of iMac you own, please call us before sending. With a Fusion iMac we take the two individual drives, not the entire iMac. Please obtain a quote via phone or through our website quote form prior to posting your drives to us. When posting your drives, please ensure they are sent using a trackable method and that they are fully insured to the value you feel is necessary. Once you have obtained a quote you may also drop off your drives at our intake laboratory located in Guildford. Our drop-off hours are Monday to Friday, 9am to 5:30pm. No appointment is required.

Only pay if we recover your data, on most jobs Diagnosis free, then a fixed quote Get a quote, then post it in from Windsor, Slough or anywhere else

Describe the fault to an engineer
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What each Fusion Drive symptom is telling you.

None of these? Run the triage →
The symptomThe likely causeStart here
Grinding noise coming from the back of your computer screenThe 3.5 inch part of the Fusion drive is mechanically failingShut down your computer and let it be
A question mark folder appears when you turn on your MacIf your volume won't mount, then one of the parts of your Fusion drive has stopped workingDon't install it again; stop here
Your iMac was knocked over while it was turned onThe heads were damaged by being knocked out of place against the moving platter(s), yet the platter surfaces often surviveUsually recoverable
Everything opens normally, however any single file takes about a minute to openThe drive reads the sectors again and again until it stops reading them altogetherTake an image of this while it reads
Disk Utility wants to "erase" then "rebuild"When Disk Utility builds a new "map", it will overwrite your existing file mapsTell Disk Utility no; the maps are the data
A T2 or Apple-silicon iMac with no passwordEncrypted by the controller, and only unlocked by that particular passwordNot taken on: it's all soldered in (if unsure, ring first)
Where to send it: first get a quote, by phone or with the form, then send it using a tracked, insured service to the Guildford intake laboratory, or drop it off there yourself (Monday to Friday, 9am to 5:30pm, no appointment needed). We will cover the cost of the postage back to you. From a laptop, PC or Mac, we just require the drive out of your computer; storage soldered to the board (T2 and Apple silicon Macs, soldered laptop flash) is not taken on, and if you're unsure as to type, call us first. From a server or RAID set, just send the individual drives, all clearly labelled by bay. From a NAS, send the disks, each labelled by bay, if they come out; otherwise, send the entire NAS unit. A single external drive comes whole, with its cable and power supply. If you wish to review your packaging before posting, contact an engineer who will walk you through the process over the phone. All steps involved with the postage process are listed on the postage page.

What is inside a Fusion iMac, and what fails.

Fusion DriveOne "logical volume" laid on top of two different types of disks. One is a small SSD, 128GB on the 2012 machines (cut down to 24 or 32GB in later models), and the other is a hard drive ranging from one to three terabytes. What you use most is stored by macOS on the faster half, and what you're not using gets moved off to the slower half, completely silently.
The iMac and Mac miniiMacs 2012–2019 & Mac minis 2012–2014. In iMacs the 3.5-inch HD and blade SSD sit behind the screen, which is stuck to the casing with adhesive. On a Mac mini there is a 2.5-inch HD and a blade under its base plate. After removing both from the case, they can be set up as standard disks on a workbench.
The mechanical halfWhere most problems start: noise, long pauses, sectors that will not read. It goes first, and it decides how the job runs.
T2, FileVault and Disk UtilityThree limitations worth knowing before you start. First Aid fixes file system damage, but does not recover data. FileVault without the password is a closed door. On a T2 or Apple-silicon machine the key is sealed in the controller, and the storage is soldered to the board, so those machines are not taken on. If you're unable to determine which type of machine you have, please contact us first.

What happens between arrival and return.

01

Booked in, then assessed at no cost Free

Nothing is chargeable until you say yes. Every item gets a case number of its own immediately upon receipt, an engineer determines what has failed, and you get a clear picture of which files have a real possibility of being recovered. The single quote that follows is fixed, written down and does not cost anything.

Diagnosis at no costOne fixed quote, in writingNothing signed
02

The display off, both drives out

Since we accept the drives from an iMac and not the entire machine, the display must be removed before posting. The adhesive holding the display in place is released, then the panel is lifted on its cables and set aside, and then both members of the drive pair behind it can be labelled and removed together.

Display and panel lifted clearThe precise fault located
03

Image each half in turn

Both volume members must be copied prior to making a single decision about the volume. The SSD copies in minutes while the mechanical half of the drive is copied in short sequential passes on a bench rig, with awkward zones deferred until the end of the process, and neither original will ever be written to.

Each half imaged firstThe originals left untouched
04

Rebuild the Fusion mapping

The map for which block sits on which member is kept by CoreStorage on the earlier machines and by APFS after that. This map is rebuilt against the two images, and full files come off these images.

The CoreStorage map rebuiltWhole files, not fragments
05

Opened, verified, and sent home

You don't get charged anything until you've confirmed and authorised that everything is fine after seeing the entire list of what was recovered. Any recovered items are returned via brand-new storage media and the postage costs for these are covered by us. We do not consider a project complete here until we receive confirmation that you have been able to successfully access and review every item you received back.

You approve the list firstReturned on fresh mediaThe return post is ours

What tends to show up first

  • One volume, two disks: in an SSD & HD combination they only mean anything when used as one, since a single file may begin on one and finish on the other. When delivered, both are labelled to show which half each one is.
  • The screen is stuck with glue instead of screws: because of the adhesive strips holding the panel (from 2012) and the short length of the cables attached to it, the panel must be separated from the frame using a small round wheel and lifted slowly. This has to be done before anything is posted. We do not receive the iMacs at the lab; we only get the drives.
  • Noise sets the clock: mechanical failure to the 3.5-inch half makes noise. A "stall" happens to macOS when a drive fails, due to repeated attempts to read the same area of the disk until a failure occurs. Every subsequent boot will use up reads the imaging process will need.
  • A T2 or Apple-silicon iMac is another unit altogether, since the controller encrypts while writing, and keeps the encryption keys to itself. The storage is soldered to the motherboard, so those units are not taken on. If you are unsure whether your unit has the T2 chip or Apple silicon, please contact us before sending anything. Without either the original password or the recovery key, the NAND storage will be unreadable by anyone.

The reason an iMac's drives typically arrive with the only copy of data stored: it spends many years sitting on a desk collecting every file made by that house or studio over a period of eight or ten years. Since Fusion presents itself as one single volume, most users do not realise that their iMac also contains a mechanical drive (a spinning disk). Most of what we see ends up in one of two ways. Either the mechanical half of the system fails and indicates failure. It starts with noise, and eventually may start making long pauses, and finally when it attempts to "mount" the volume it is unable to complete the process. Or, a newer system will shut itself behind a controller that will not give up its encryption key. The first is repairable on our bench; the second requires knowing a user's password. Describe the noise and we will tell you which you have.

From the casebook, lately.

MH · MHD-2026-6841ON RECORD ✓

The iMac that was still in use, a fortnight into the noise

The drive had been grinding for two weeks at this time and was still being used daily, which is the part that costs the most. The display unit was removed, the two parts (members) of the pair were identified by label and removed, and the noisy 3.5-inch hard disk was imaged over multiple sessions; the easy sectors were done first, then the SSD was copied in just a few minutes. The CoreStorage map was rebuilt using the two images and all files were recovered intact. Three days after receiving it.

100% imaged3 days from arrival

Before the drives come to the lab.

Do these now

  • Obtain a price quote first, then send both disks together, each labelled with which member it is
  • Send your login password and the recovery key if you have them
  • Shut down the computer and leave it off
  • Advise what year your iMac was made

Things best not done

  • Running it up again to gauge how much worse the noise is
  • Using Disk Utility to wipe or rebuild the volume
  • Installing a new copy of macOS on top of the failing volume
  • Removing the display without using a tool

The questions that arise most often.

My iMac has begun grinding — can I keep working on it?

Grinding or a repeated thumping noise from inside the 3.5-inch half of your Fusion Drive indicates mechanical damage versus a problem with the software. Your slow performance has the same cause; when you are trying to access something but keep getting "read errors" then the system will attempt those reads over and over again and then move on. Every time you boot up, it uses up reads you may want later, so turn it off at the wall and let it sit until you have spoken to an engineer.

Only the hard-disk half has failed. Is my data still there?

Very likely yes, but not from just that half on its own. Apple puts one single logical volume (CoreStorage on the earlier units, APFS on the later ones) over a small solid-state drive (SSD) and a hard disk. It also spreads the data showing which blocks exist in each place over both. This means that once a file starts writing on the SSD it can end up on the disk. So, reading the remaining portion of either of these will give fragmented files with little-to-no filename information. Thus, what needs to occur is imaging both parts, then rebuilding this block mapping against the two images.

Do I have to take the display off to reach the drives?

The display portion of an iMac is under-estimated by many. Since 2012, all iMac displays are secured using adhesive strips instead of screws. Therefore, those strips need to be cut through, the display lifted while keeping the cables connected, and new adhesive strips installed on the way down; both drives sit directly behind the panel. As we take the drives and not the entire iMac unit, they do need to be removed. If you don't want to try it let us know when you call and we'll discuss other options prior to sending anything by post.

My iMac has a T2 chip and the password is lost. Now what?

Honestly speaking, nothing can be recovered from such a device. Any Apple machine with a T2 processor, like newer iMacs, and any Apple silicon-based machine encrypts its storage at time-of-write using its silicon-based controller and stores the decryption key within that same silicon. The decryption key is only released upon entering your password or recovery key. There isn't a lab in Britain capable of accessing the NAND without access to the key. Older Fusion iMacs (pre-2018) that were never activated for FileVault are a different matter.

More of the jobs we've closed.

Fitted drives → Noisy drives → No drive detected → Media we work with →

Switched off, it keeps every chance it has.

Every additional power-up asks for even more of a drive that is already starting to fail. First open a case with us, and let the free diagnosis tell you how much remains.

0800 6890668

Ask for a free diagnosis Posting it to us