Size first, then what happened
Every kind of NAS, and how each one fails. The box tells us how the drives were joined; the drives hold the rest.
A NAS is a small Linux computer with some drives in it, and when it fails the drives hold the data and the computer holds the only record of how it was arranged. What decides the job is not the badge but the box: how many drives, how they were joined, whether a cache sat in front of them, whether a key was involved, and what was done to it after it stopped. Pick yours below. A single-drive NAS is £300 + VAT, a two-bay unit or any RAID, SHR or mirrored set is £500 + VAT upwards, and four bays, rack units and larger arrays start at £1,250 + VAT, with the figure in writing after the free look and no data meaning no bill on most jobs.
Rather talk it through? An engineer answers the bench line
0800 6890668
By the size of the box, or by what happened to it.
Rather begin with what it says →By the size of the box
Single-bay NASMy Cloud, a one-bay Synology or QNAP, a LinkStation: one drive with a system partition and an ext4 or Btrfs volume. £300 + VAT→Two-bay NASMirror, SHR or RAID 0 across two drives. The classic loss is the second drive during the resync, or the wrong one pulled→Four-bay RAID 5 and 6SHR, X-RAID, TRAID and plain RAID 5 or 6: every member imaged, the layout read from the metadata, the set rebuilt from images→Rack and SMB NASEight to twenty-four bays, several pools, iSCSI LUNs and a cache. Send the drive list by bay→TrueNAS, Unraid, OMVZFS vdevs, Unraid parity, mdadm under OMV. The drives are yours and so, usually, are the mistakes made in the shell→NAS with SSD cacheA read-write cache holds data the hard drives never received. Send the cache SSDs with the set→By what happened to it
Encrypted volumes and foldersSynology LUKS and eCryptfs, QNAP and Asustor encryption. We bring the array; you bring the key→Cloud appliancesMy Cloud Home, My Book Live, Seagate Personal Cloud: proprietary layouts and coded filenames that need their database→NAS hit by ransomwareDeadbolt, Qlocker, eCh0raix. What snapshots, deleted originals and the tails of files still hold→Failed update or migrationA DSM or QTS update that bricked the boot, a reshape that stopped half-way, a migration that failed→Dead unit, drives finePSU, board, memory. The drives carry everything; the order they were in is what matters now→iSCSI LUNs, VMs and DockerA volume inside a volume: the pool is rebuilt first, then the LUN, the VM disk or the container storage inside it→Why the box matters, and why it never matters as much as the rebuild button.
Almost every NAS sold in Britain runs Linux, joins its drives with the kernel's own software RAID, mdadm, and puts a file system on top: ext4 or Btrfs on Synology, QNAP, Asustor, TerraMaster and WD; XFS on Buffalo; ZFS on TrueNAS and QNAP's QuTS hero. The makers' own names, SHR, X-RAID, TRAID, BeyondRAID, are layouts built on those parts, and each is reconstructed from images of the drives rather than read by putting the drives in a PC, which offers to format them.
What decides how a job turns out is rarely the layout. It is what happened between the first failure and the parcel. A degraded set that was powered down is a good job. A degraded set that was asked to rebuild, met a second weak drive at 38 per cent, and was then reset, reinstalled or moved to another unit in a different order is a harder one. Every page on this site says the same thing first, because it is the thing that most matters: power it down, label the bays, and let nothing rebuild.
The rest is bench work: the unit tested on its own, each drive imaged, the set reassembled from the images with the order and geometry read out of the drives' own metadata, and the file system repaired on the virtual volume before the files are copied out. There is more on that on What is inside a NAS, and a page for each make on the manufacturers page.
The questions that come up first.
Do I send the whole NAS or just the drives?
The drives, always, labelled by bay, and the unit too where it holds an encryption key, a proprietary layout, or a cache. The form asks which; if in doubt, send both, with the power supply.
Can I read the drives in a PC?
No. They are Linux RAID members, and Windows will offer to initialise them. Even a single-drive NAS carries a system partition and an ext4 or Btrfs volume a PC does not read without help.
Why is a rebuild dangerous?
A rebuild reads every sector of every surviving drive to write the missing one. If any survivor is weak, the rebuild stalls on its bad sectors or drops it, and a degraded set becomes a failed one. The bench images each drive first and rebuilds from the images, where nothing can be lost by trying.
Does the kind change the price?
By the number of drives. A single-drive NAS is £300 + VAT; a two-bay or any set is £500 + VAT upwards; four bays, rack units and larger arrays start at £1,250 + VAT. The figure is written down after the free look, and on most jobs no data means no bill.
Not sure which one you have?
Photograph the back of the unit and the drive bays and send them with the form. The model number is enough to tell, and the first look is free whichever kind it turns out to be.