Data Recovery Case File · Mac & Apple Ecosystem · Scope It to the Volume
A Drive With Several Volumes Can Lose One and Keep the Others
Her enquiry scopes itself better than most and contains a distinction worth drawing out. A drive that "won't mount on any of my machines. I'm a designer and photographer and this drive has all of my files on. It has a few partitions, and the data I need retrieving is 270GB" from one of them. Mounting is something volumes do, not drives — and on a drive carrying several, damage to one leaves the rest entirely unaffected.
| Media | 1TB hard drive carrying multiple partitions — one volume not mounting; approximately 270GB of professional content required from that volume |
| Reported situation | Drive not mounting on multiple host machines · drive carrying several partitions · professional design and photographic content held · approximately 270GB required from one identified volume · other volume status not stated |
| Fault class | Volume-level fault to be distinguished from device-level failure — partition table readability determinative; scope confined to one identified volume |
| Equipment used | Device enumeration and partition table readability distinguished from volume mountability · other volumes assessed independently · imaged write-blocked with capture sequenced to the required volume · structures rebuilt from surviving copies · files validated by opening |
The decode: three layers, and which one has failed
The device layer: whether the drive presents itself at all and reports a capacity. If it does, the hardware is doing its job and everything above it is a separate question.
The partition layer: a small structure at the very start describing where each volume begins and ends. If that reads, the system knows the drive has several volumes and where they are — even if it cannot use any of them.
The volume layer: each partition carries its own independent filesystem. They are separate structures that fail separately, which is the point people miss when they say a drive will not mount.
Why the distinction is practical rather than pedantic: if the device presents and the partition table reads and one volume will not mount, the fault is confined to one filesystem on a working drive — which is a bounded, well-understood and highly recoverable position. If nothing appears at all, it is a device-level fault and a different job entirely.
The check that establishes it, and it is free: open the disk utility and look at whether the device is listed with its partitions beneath it. Partitions visible and one refusing to mount is the good version; nothing listed is the other one.
Why the other volumes matter as evidence: if they mount normally, the drive is demonstrably readable in those regions. That localises the fault to the area holding the affected volume, and it means the surface is not uniformly failing.
Why her scoping is worth having: she has named the volume and the quantity, which means capture can be sequenced to reach that region first and confirm it early — rather than reading the whole drive before anybody knows whether the work survived. For a professional with client material, confirmation timing is most of the value.
What working practice frequently means here: designers and photographers commonly partition a drive to separate current work from archive. If the affected volume is the archive, it may be the least-written and therefore the healthiest region; if it is the working volume, it has seen the most activity. Worth establishing which.
What must not happen: no repair on the affected volume, and no initialisation of the drive. Initialising replaces the partition table, which is currently the thing holding the other volumes together.
On the bench
Device enumeration and partition table readability were distinguished from volume mountability — a drive presenting itself with a readable partition structure while one filesystem fails to mount confining the fault to that volume, since each partition carries an independent filesystem that fails separately. Other volumes were assessed independently, their mounting demonstrating the surface is readable in those regions. Imaging ran write-blocked with capture sequenced to the required volume.
The outcome
Enumeration and partition readability separated from mountability, other volumes assessed independently, and capture sequenced to the volume required. 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: mounting is something volumes do. A drive carrying several partitions has several independent filesystems that fail separately — so if the device appears with its partitions listed and one refuses, the fault is confined to that one.
Drive with several partitions that will not mount
Open the disk utility and check whether the device appears with its partitions listed beneath it — that distinguishes two quite different situations. Each partition carries its own independent filesystem, and they fail separately, so a drive presenting normally with a readable partition structure and one volume refusing to mount has a fault confined to that single filesystem, which is bounded and highly recoverable. Nothing listed at all is a device-level problem and a different job. If your other volumes still mount, that's evidence too: the surface is demonstrably readable there. Don't run a repair on the affected volume, and never accept an offer to initialise the drive.
Check whether the partitions still list — then call Oxford Data Recovery on 01865 593000; enumeration separated from mountability, other volumes assessed independently, capture sequenced to the volume you need.
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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.