Data Recovery Case File · Mac & Apple Systems · The Machine Changed, Not the Drive
A System Upgrade Can Alter Which Volume Formats a Machine Will Mount
This enquiry places a failure precisely in time and asks a practical question alongside it. A backup to an external drive that worked without problem, then a system upgrade installed in a shop, after which the drive is "recognised but refuses to mount" — on other machines too, spinning audibly with its indicator active. The drive did not change and the machine did, and the question of whether to spend on a newer computer or on recovery has an order to it.
| Media | External hard drive holding a system backup — enumerating and refusing to mount following a host operating system upgrade; rotation and indication present |
| Reported situation | Laptop backed up to an external drive without difficulty · operating system upgrade installed subsequently · external drive recognised but not mounting afterwards · mounting attempted on other machines of both platforms without success · rotation audible and indicator active · owner weighing replacement of the machine against recovery |
| Fault class | Volume not mounting following a host upgrade — format compatibility and structural damage both open; device demonstrably functional at hardware level |
| Equipment used | Timing against the upgrade assessed before any hardware fault was assumed · volume format and structures read directly from a write-blocked image · conversion state examined for partial or interrupted upgrade of the backup volume · filesystem structures interpreted with their duplicate copies · content extracted from the image independently of any host |
The decode: what an upgrade changes, and the order of the decision
What the rotation and indicator establish: the hardware works. A drive that spins, lights and is recognised has completed everything a mechanical or board fault would have prevented.
Why that eliminates the expensive outcomes at the outset: nothing here points at heads, motor or electronics. The obstacle sits at the volume rather than the device.
What a major system upgrade does to storage: it can change the filesystem in use. Newer versions introduce new volume formats and convert internal storage during installation, and their handling of older external volumes can differ.
Why an external backup volume is particularly exposed: it may be converted or partially converted. A backup volume presented to an upgraded system can be offered for conversion, and an interruption leaves it between formats.
Why other machines failing too is consistent with that: a volume in an inconsistent state is inconsistent everywhere. Trying additional computers eliminates the original machine without eliminating the format question.
Why it was nonetheless worth doing: it removed a whole category. A drive failing identically on several hosts is failing for reasons that travel with it.
What the alternative explanation is: the upgrade is coincidental. A backup volume can develop structural damage independently, and an upgrade involves heavy reading and writing that surfaces it.
Why the two are distinguished by examining rather than testing: the volume's own structures record which format it is in. Reading them from an image settles it without asking any machine to mount anything.
Now the decision he raises, which has a clear order: the backup is the only copy of whatever the laptop no longer holds. A newer machine does nothing to recover it, and buying one first risks the drive being written to during setup.
Why that ordering matters more than the sums: the content is not replaceable and the machine is. Establish what the drive holds and what it costs to reach it, then decide about the computer.
On the bench
Timing against the upgrade was assessed before any hardware fault was assumed — rotation, indication and recognition establishing hardware function and placing the obstacle at the volume. Major system versions introduce new volume formats and convert storage during installation, and external backup volumes may be offered for conversion, with interruption leaving them between formats. Identical failure across hosts indicates a cause travelling with the drive. Conversion state was examined from a write-blocked image.
The outcome
Timing assessed before any hardware fault was assumed, volume format read directly from an image, and structures interpreted with their duplicate copies. Free assessment, one fixed written figure including VAT; where a drive has to be opened, 50% of parts and labour is payable upfront with the balance only on success — otherwise no recovery, no fee. The decode: your drive spins, lights and is recognised, so the hardware is fine. What changed was the machine — and a newer one recovers nothing, so settle the drive first.
A backup drive that stopped mounting after an upgrade
Settle the drive before buying a new machine — a replacement recovers nothing, and setting one up risks the drive being written to. Read what you have as encouraging: spinning, lit and recognised means the hardware completed everything a mechanical or board fault would have stopped, so the obstacle is at the volume. Major upgrades introduce new volume formats and may offer to convert an external backup, with an interruption leaving it between the two. Trying other machines was worth doing, and it rules out the computer rather than the format.
Settle the drive first — call Cambridge Data Recovery on 01223 655015; timing assessed before hardware is blamed, format read from a write-blocked image, structures rebuilt from duplicate copies.
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Our case files are drawn from genuine enquiries received by our laboratory over the past ten years, anonymised to protect client confidentiality. Each one describes the diagnostic and recovery procedure our engineers apply to that fault, using the equipment listed.