Unraid · parity · XFS · Btrfs · ZFS · cache pool
Unraid NAS data recovery. One disk, one file system, which is good news.
Unraid does not stripe. Each data disk carries its own complete file system, XFS, Btrfs or ZFS, and one or two parity disks protect against a failure; a single data disk can be read on its own, which is why Unraid is the most forgiving platform on the bench. The losses come from parity: a rebuild run with the wrong disk assigned, or against a second disk that was already throwing errors, writes bad data onto a good disk. A disk showing unmountable is usually a damaged file system on an intact disk, and the dashboard's offer to format it is the one to refuse. A single data disk is £300 + VAT; a set with parity is £500 + VAT upwards, in writing after the free look.
Rather talk it through? An engineer answers the bench line
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Models we see, family by family.
Which kind of unit is it →| Family | Models | Bays, OS, file system and layout |
|---|---|---|
| Array | Data disks with one or two parity | Each disk its own XFS, Btrfs or ZFS |
| Cache | Btrfs or ZFS pool | Holds recent writes until the mover runs |
What tends to go wrong on a Unraid.
Unraid symptoms, and how long each gives you.
Not listed? Describe it on the form →What the message means on a Unraid.
Describe yours to us →| What you see | The usual reason | Where that leaves you |
|---|---|---|
| Pool or volume degraded | One member lost; still readable | Copy critical files; power down; no rebuild |
| Pool or volume crashed / unmounted / not active | Too many members lost, or file system damage | Every member imaged; assembled from the superblocks |
| Unit will not boot after an update | System partition or boot flash; data intact | Data arrays assembled without the OS |
| Drives shown as new in another unit | Foreign layout; the unit offers to install | Say no; the order is read from the metadata |
From the box arriving to your files going back.
Work we have closed →Logged the day it lands, and the first look costs nothing Free
A case number goes on the parcel and a number on every drive the day it is opened, and an engineer settles what has actually happened before anything spins. The unit is examined on its own; each drive is assessed on our own equipment, never in a NAS that will try to rebuild. Back to you come two things together: a straight note of what is liftable and what is not, plus one figure, fixed and written down. Accept it, or decline and owe us nothing.
The unit, and the drives, apart
The box and the disks are two different jobs. The unit is tested separately, because a dead power supply, a failed board or a bricked boot flash leaves the drives untouched more often than not. Each drive is then read on the bench: the ones that answer at full speed, and the weak or failed ones in clean air where they need head work. On units that hold an encryption key or a layout of their own, the unit is part of the data and is kept with it.
Every member imaged, once
Nothing is worked on live and nothing is rebuilt on the originals. Every drive in the set is imaged sector by sector, the weak ones head by head with the bad areas last, and the SSD cache with them where there is one. From then on the originals are not touched again.
The set put back together, from the images
Order, chunk size, parity rotation and the reshape point are read from the drives' own metadata and the array is reassembled in software: mdadm and LVM under SHR, X-RAID and QTS pools; a ZFS pool imported read-only; Drobo's BeyondRAID zones reconstructed. The file system, Btrfs, ext4, XFS or ZFS, is repaired on the virtual volume, and encrypted volumes are unlocked there with the key you supply. Never on the originals.
You see the file list before you pay
What was recovered is listed for you first, and only then does a bill exist. Approve the list and it is invoiced; turn it down and it is not — and where nothing has come back, most jobs carry no charge at all. Recovered data travels home on fresh media bought in for your job, with the postage at our end. Your case is not closed until you have opened the files on a machine of your own.
From the bench
- Linux, mdadm, LVM and a file system. The maker's names for the layout sit on the kernel's own RAID, and every layer writes its description on every drive. The bench reads it from the images and needs nothing from the unit but its key.
- A rebuild reads every sector of every survivor. On drives that have aged together it is where the second failure is found. The bench does the same arithmetic on images, which cannot drop out.
- Label the bays. The metadata usually gives the order; the label makes it certain, and a set whose drives were swapped and initialised is a harder job.
What helps, and what harms.
Do this much first
- Power down and label the bays
- Send every drive, the unit and its supply
- Tell us the OS version, the RAID mode and what was clicked
- Find the encryption key if one was set
What sets us back
- Rebuilding, repairing or resyncing
- Reinstalling the OS or factory resetting
- Moving the drives to another unit
- Initialising drives the unit shows as new
Questions answered before you commit.
Unraid says a disk is unmountable. Should I format it?
No. The disk's file system is damaged and the data is intact beneath it; the format prompt is the one to refuse. The disk is imaged and its XFS or Btrfs repaired on the image.
Can a PC read the drives from my Unraid?
No. They carry a Linux volume, usually over mdadm, and a PC offers to initialise them. They are mounted from images on the bench.
What does it cost?
£300 + VAT for a single-drive unit; any set is £500 + VAT upwards, fixed in writing after the free look.
How long does it take?
5–10 days at the bench for a set; 3–4 days at the bench for a single drive.
Begin here if yours is doing the same thing.
Nothing gets worse while it is powered down.
Looking at it is free. Back comes a list of what opened and what did not, together with a single price to finish, set down in writing while you are still free to say no. On most jobs an invoice only follows the data. Until that list reaches you, leave the unit off and the drives in their bays.