Pooled NAS storage · job record · ADR-2025-2891
One Member Clicked, and Both Disks Went With It.
Two disks, one pool, and a FreeNAS box that had been dependable enough that nobody thought about it from one month to the next. The first sign was a sound rather than a message: he heard a clicking sound
shortly before the volume stopped answering. His own reading of it was accurate — 1 drive is causing the problem
— and so was his account of what followed, since a pool laid across a pair makes both drives inoperative
the moment one of them goes. Then the sentence that decides how carefully everything after it is handled. He didn't back it up
.
Same story on yours? Tell us what it does — the look is free.
0203 0868633
What failed, and why.
A pool is not two disks sitting side by side. FreeNAS spreads one storage system across its members, so what any single disk holds is a part rather than a half, and a serious fault in one of them can put the whole pool beyond reach. That is ordinary pool behaviour and not two failures at once, which is why the box reported everything unavailable when only one member had anything wrong with it. The clicking narrowed the rest. A noise of that kind is mechanical, which puts the fault in the heads rather than anywhere in software, and it means each further start-up spends a little more of whatever the surfaces still hold in reserve. So the unit stayed off. The temptation at that point is to fit a replacement disk and let the box resilver, and a resilver writes new metadata straight over the ground a rebuild depends on reading. Anything with a second disk in it is published from £500 + VAT. Diagnosis is not charged for.
What the bench did with it.
The order of the job →| Equipment used | Its work on this job | The reason for it |
|---|---|---|
| DeepSpar Disk Imager 4 | Both members copied behind a write blocker, the clicking one only after its heads were renewed | Heads mapped first, then one platter side to a pass, with every reset, every timeout and the power itself kept under our own control |
| Atola TaskForce 2 | The sound disk and the repaired one read in parallel instead of one waiting on the other | All members of a set copy at once, so no disk sits waiting on another |
| UFS Explorer RAID Recovery | The pool's own labels read off the images, then the shares assembled from copies | Recovers the stripe order, then unpicks the volume manager the NAS layered above it |
What the bench did with it.
Neither disk was started in the box again
Both disks were assessed before either was read: draw profiled on a bench supply, firmware questioned, health figures read off each in turn. The clicking member behaved exactly as he had described. The other was serviceable. Nothing was put back into the FreeNAS to see what it would do, because a pool that finds a member absent will set about resolving the matter itself.
Heads first, in clean air
The failed member was opened under laminar flow and its heads and platters examined under a stereo microscope. The surfaces had come through it; the head assembly had not, which is the usual arrangement behind steady clicking. A matched donor assembly went in. From there the disk was only ever read — it was never asked to serve a volume again, and nothing was written to it at any stage of the job.
Rebuild the pool away from the box
Both images then went to software that understands how a pool of that kind is laid out, and the pool was assembled from the copies. Nothing about the arrangement was assumed: member roles and the pool's own labels were read from what the disks had written about themselves, since a guess at that level produces a volume that mounts and is wrong. What came out was checked file by file before any of it was called recovered.
What went home.
Everything the pool held went home on fresh media, opened and checked here first. He had said plainly at the start that none of it existed anywhere else, and that is the sentence that sets how a job like this one is run: one prepared attempt, made properly, with nothing tried on the originals. The box itself was never part of the answer.
Begin here if yours is doing the same thing.
Other RAID & NAS work on the log.
Yours doing something similar? Power it down first.
Prices are published and fixed. Memory cards and USB sticks are priced at £250 + VAT. A drive on its own comes to £300 + VAT. Anything holding a second disk, whether RAID, NAS or a server, opens at £500 + VAT. The first look costs nothing, and the figure that follows is fixed and in writing before a penny is charged. Switch it off and post it in. Most jobs carry no fee where no files return.