NDR / Every kind of NAS / Rack and SMB NAS

Synology RS · QNAP TS-U and TVS · TerraMaster U · ReadyNAS 2120, 3138 · 10GbE

Rack and SMB NAS. Several pools, a cache, a few LUNs, and a business waiting on all of them.

A rack NAS is the same Linux, mdadm and LVM as the desktop units, at a scale where the mistakes cost more: eight to twenty-four bays, more than one storage pool, an SSD cache in front of the hard drives, iSCSI LUNs serving a hypervisor, and snapshots that were meant to be the backup. They arrive with a pool crashed after a double failure, a rebuild that ran into a third weak drive, a cache that died with dirty data in it, or a controller that forgot which drive was which. Rack units and arrays of eight bays or more start at £1,250 + VAT after the free look, fixed in writing, and take five to ten days at the bench; the drive list by bay is the first thing we ask for.

Free first lookOne fixed figure in writingNo data, no bill on most jobsReturn postage paid

Rather talk it through? An engineer answers the bench line
0800 6890668

Power it down. Label each drive with its bay number. Do not rebuild, repair, initialise, reinstall or reset. A rebuild reads every sector of every surviving drive, and on a set with a second weak member it finishes what the first failure began. Nothing on the drives gets worse while the unit is off.

Rack unit symptoms, and what each asks of you tonight.

Not listed? Describe it on the form →

Pool crashed after a second drive failureTwo members lost. Power down; no rebuild.Do not delay

Rebuild stalled on a third driveA survivor with read errors. Power down.Do not delay

The SSD cache failed and the volume will not mountDirty data in the cache. Send the cache SSDs with the set.Do not delay

The unit lost its configuration; drives shown as newController board or its metadata. Do not initialise.Do not delay

An iSCSI LUN is gone with the poolThe LUN is a file or block range inside the pool; the pool is rebuilt first.Do not delay

The unit will not boot; the pools are fineBoot flash or board. The drives carry the pools.Everyday job

Packing it and posting it: power the unit down, write the bay number on each drive with a marker before it comes out, and send every drive from the set, including any SSD cache. Each drive travels in an anti-static bag inside its own padding, in a box with nothing able to move; the unit itself comes too if it holds an encryption key or a proprietary layout, and its power supply with it. Insure the parcel for what the files are worth rather than the price of the drives, and use a tracked service. The posting address is not printed anywhere on this site; it arrives by email in reply to the form, with a booking sheet to print; the sheet inside the parcel is what matches it to your enquiry when it is opened. Or hand the sealed parcel in at the nearest of ten drop-off points, your name on the outside and the sheet inside; say where you are on the form and it comes by email. We pay the postage home either way. The whole of it is written up on the guide to packing and posting.

How it is laid out, and what fails.

Several pools, one unitEach pool is its own set of mdadm arrays and LVM volumes, and each is assembled separately from the images of its own members. Send every drive from the unit, marked with its bay; the bench sorts them by the metadata.

SSD cacheA read-only cache can be discarded. A read-write cache holds data the hard drives never received, and a volume with a dead read-write cache will not mount cleanly until the cache's contents are merged from the SSD images.

iSCSI LUNs and VM storageThe pool is rebuilt first, then the LUN, which is a large file or a block range on the volume, and then the VMFS, NTFS or ext4 inside the LUN. Three file systems, one on top of another, each repaired on the image of the one beneath.

SnapshotsBtrfs and ZFS snapshots survive on the drives even when the current volume is damaged, and are often the cleanest copy of the data. They are found on the reassembled images.

What it says, and what it means.

Describe yours to us →

What you see	The usual reason for it	Where that leaves you
Pool crashed	Two members gone in RAID 5, three in RAID 6	Every member imaged; parity run on the images
Rebuild stalled	A survivor's unrecoverable read errors	Weak member imaged with bad areas last; set rebuilt from images
Volume will not mount; cache failed	Dirty read-write cache	Cache SSDs imaged; contents merged
Drives shown as unused / new	Controller lost its configuration	Order and geometry from the superblocks
LUN missing	Pool below it damaged	Pool, then LUN, then the file system inside

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.

Nothing to pay for lookingA single figure, put in writingNo rebuilds, no repairs, no resets

The unit, and the drives, apart

A rack unit arrives as a drive list before it arrives as a parcel. Every drive is read on its own, sorted into its pool by the metadata, and the weak members go to the clean bench; the cache SSDs are imaged with the set. The unit's board is kept for its configuration and any key it holds.

Unit and disks assessed separatelyFailing members to the clean bench

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.

Every drive, including the cacheWeak areas last

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.

Rebuilt in software, from imagesThe file system repaired on the virtual volume

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.

No charge until you accept the figureFresh media, supplied with the jobFive to ten days at the bench

What arrives most often

Send the drive list by bay before the drives. Make, model, size and bay for every drive, and which pool it belonged to if you know. It shortens the job by days.
Send the cache SSDs. A read-write cache is part of the data, and a set without it mounts with holes where the last writes were.
Stop every rebuild, resync and scrub before the unit is powered down, and do not start any on the way to the parcel.
Snapshots are often the answer. Where the live volume was damaged by a rebuild or by ransomware, the last snapshot on the reassembled images is frequently intact.

One job, followed all the way through.

UK · NDR-2026-0548JOB LOGGED ✓

A Synology RS1221+ with eight drives in RAID 6, two failed, a third dropping during the rebuild, and a hypervisor's LUNs on it

The unit was powered down when the third drive dropped, which saved the job. All eight drives were imaged, the third slowly with its weak areas last; the RAID 6 was assembled from the images with the geometry read from the superblocks, the LVM volume mapped, the Btrfs file system mounted read-only, and the three iSCSI LUNs extracted and their VMFS volumes opened in turn. The virtual machines came back complete.

100% of the LUNs recovered9 days here, and back by post

Illustrative example — replace with a genuine case

What helps, and what harms.

Do this much first

Power it down and stop every rebuild and scrub
List every drive by bay before it comes out
Send every drive, the cache SSDs, the unit and its supplies
Tell us the pool layout, the LUNs and the OS version

What sets us back

Rebuilding after the second failure
Initialising drives the unit shows as new
Removing the cache and mounting without it
Moving drives between bays or to another unit

Questions answered before you commit.

Two drives failed in my RAID 5 rack unit. Is the data gone?

Usually not. The drive that failed first still holds the stripes written before it dropped, and the second usually reads on the bench with its bad areas taken last. Every member is imaged and the parity is run on the images.

Do I need to send the SSD cache?

If it was a read-write cache, yes: it holds data the hard drives never received. A read-only cache can stay.

Can you recover the iSCSI LUNs?

Yes. The pool is rebuilt first, then the LUN, then the VMFS, NTFS or ext4 inside it, each on the image of the layer beneath.

What does it cost?

Rack units and arrays of eight bays or more start at £1,250 + VAT after the free look, fixed in writing for the set.

How long does it take?

Five to ten days at the bench for most sets, longer for very large ones, and the figure says which.

Begin here if yours is doing the same thing.

iSCSI LUNs, VMs and Docker →NAS with SSD cache →Four-bay RAID 5 and 6 →Synology →QNAP →

Send the drive list first. Then the drives.

Every member imaged, the pools reassembled from the images, and one figure for the set in writing before any chargeable work. The first look is free.

0800 6890668

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