Data Recovery Case File · NAS & Network Storage · A Backup on the Same Circuit
A Copy Only Protects You Against Risks the Original Does Not Share
His enquiry describes a backup arrangement that failed for the reason backups exist and in the way they are least expected to. Two 5TB drives, one holding a media collection and one holding its backup, where after a power cut "neither the storage drive nor the backup are working — both totally dead, no power light at all." Two drives on one supply are not two chances: a single electrical event reached both simultaneously.
| Media | Two 5TB external drives, one serving as storage and one as its backup, both connected to the same mains supply — neither powering following a supply interruption |
| Reported situation | Two external drives in use as store and backup for a media server · both connected at the time of a supply interruption · neither drive powering afterwards · no indication on either · substantial media collection held on both · recovery sought |
| Fault class | Simultaneous power-stage failure from a common electrical event — both devices sharing the exposure; recorded content not implicated by the mechanism |
| Equipment used | Common-mode exposure identified as the reason both failed together · each drive assessed separately rather than as one job · adapters excluded from all testing · drives powered independently on a controlled bench supply with draw measured · board examined at component level under current limiting |
The decode: why both went, and what it says about the arrangement
What a power cut actually delivers: often more than an absence. Supply is frequently restored abruptly, and the restoration can carry a surge — which is the part that damages equipment rather than the interruption itself.
Why both drives received it identically: they were on the same supply at the same moment. Whatever arrived at one arrived at the other, and they had the same protection against it, which is to say the same components in the same arrangement.
Why that is the substantive lesson rather than bad luck: a backup protects against a failure the original does not share. Two drives on one circuit share the electrical risk completely, so against that particular hazard the second drive was never a second copy.
Why the same applies to more than power: two drives in one room share theft, fire, flood and mains. A copy in the same place is protection against device failure and nothing else — which is worth knowing rather than discovering.
Why no indication at all is a favourable symptom: the failure is at the power stage. An indicator lights as soon as power reaches the board, before the drive does anything, so darkness places the fault at or before that point.
What that means for the recording: nothing has reached it. An electrical event travels through circuitry and has no path into the sealed assembly, so the platters hold what they held.
What the likely damage is: the mains adapters, the enclosure boards, or the drives' own power circuitry. Boards carry components designed to fail first under excess voltage, and a failure there is frequently that protection having worked.
Why the adapters must be set aside rather than reused: if a surge damaged them, they may now deliver incorrectly. Testing either drive with either original adapter risks repeating the event.
Why the two must be assessed separately: identical exposure does not mean identical damage. One may have lost only its adapter while the other lost a board, and the cheaper of the two is worth finding first.
Why that ordering saves money: the drives hold the same content. Recovering whichever proves easier answers the whole question, and there is no need to recover both.
On the bench
Common-mode exposure was identified as the reason both failed together — supply interruptions frequently being followed by abrupt restoration carrying a surge, which reaches every device on the circuit identically and meets the same protective arrangement in each. Absence of indication places the fault at or before the power stage, an indicator illuminating as soon as power reaches the board. Electrical events travel through circuitry without a path into the sealed assembly. Adapters were excluded from all testing.
The outcome
Common-mode exposure identified, each drive assessed separately, and both powered independently on a controlled supply with draw measured. Free assessment, one fixed written figure including VAT, quoted per drive; 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: they were never two chances against this. A backup protects against risks the original does not share, and two drives on one circuit share the electrical risk entirely.
When a power event takes the drive and the backup together
Set both mains adapters aside and don't test with them — if a surge damaged them they may now deliver incorrectly, and reusing one repeats the event. Have the two drives assessed separately, since identical exposure doesn't mean identical damage and they hold the same content, so recovering whichever proves easier answers the whole question. The lesson worth keeping: a copy only protects against risks the original doesn't share, and two drives on one circuit share power, and also theft, fire and flood.
Set the adapters aside — call Manchester Data Recovery on 0161 871 0788; common-mode exposure identified, each assessed separately, powered independently on a controlled supply with draw measured.
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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.