RDD / Whatever it is saying now / SAS drive not detected

not detected · Missing · backplane · expander · cable · firmware · SED · 520-byte

A SAS drive is not detected. Half the time it is the slot. The other half, the drive already said so.

A drive that the controller cannot see is one of five things: a backplane slot or expander port that has failed, a cable or a connector that has worked loose, a drive whose firmware will not bring it ready, a self-encrypting drive or a 520-byte drive that the host sees and refuses, or a drive that has died. The first two are fixed with a screwdriver, the third and fourth on the bench, and the fifth on the clean bench, and the checks that tell them apart take five minutes and must not turn into a run of reseating, swapping and power-cycling that finishes a drive that was only waiting for the right host. One member imaged is £300 + VAT after the free look, fixed in writing, 3–4 days at the bench.

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

Look at the controller log and the drive's LED before anything is reseated. A drive with an amber LED, or one the log shows failing before it vanished, has a fault and the slot is beside the point: power down and send it. Only a drive whose log is clean gets the checks below.

The checks, in order, and where each one stops.

First, the log and the LED. A PERC, a Smart Array or a MegaRAID logs every state change, and a drive that reported predictive failure, timed out, or was dropped before it disappeared is a drive with a fault. Its carrier LED says the same: amber, or a green-amber pattern, is a fault, and no light at all on a backplane that lights the others is a slot or a drive that is not taking power. Read those first. A drive with a fault in the log gets no further checks; it gets powered down and sent.

Then the slot, once. A drive whose log is clean can be moved to a known-good slot in the same backplane, with the server off, once. If it appears, the slot or the expander port is the fault and the drive is fine; if it does not, the drive is the fault and nothing further should be tried. The same drive should not be tried in another server, and never on a desktop SATA port: a SAS drive will not fit and a SATA one will be offered for initialising.

Then the three that are not faults. A self-encrypting drive whose controller was replaced is detected and reports ciphertext or a locked state; a 520-byte drive from a storage array is detected and refused as an incompatible sector size or 0 GB; a 4Kn drive in a host that expects 512-byte sectors reports the wrong capacity. All three are drives with nothing wrong that need the right host or the right key. And beneath all of it, a drive that spins up and is not detected, or spins up and down, has firmware or heads that will not bring it ready, and that is a bench job the checks cannot help.

What it says, and what it means.

Describe yours to us →

What you see	The usual reason	Where that leaves you
Not detected; carrier LED off; other slots lit	Slot, backplane or the drive not taking power	Try one known-good slot, server off
Not detected; log shows predictive or timeout before	The drive	Power down; send it
Detected as 0 GB or incompatible sector size	520-byte or 4Kn drive	Not a fault; imaged at native size
Detected as Secured / Locked	A SED without its key	Find the key
Spins up and down; not detected	Firmware or heads	Power down; bench
Several drives vanished at once	Backplane, expander, cable or supply	The host; the drives are usually fine

From the parcel 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, matched to the slot you wrote on it. An engineer settles what has actually happened before anything spins: the interface, the sector format, the firmware, the security state, and what the controller was saying when it stopped. 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 imports, no resets

The drive on its own bench

A member drive is read on the equipment its interface needs: a SAS imager for SAS and NL-SAS, a SATA imager for enterprise SATA, a terminated SCSI or Fibre Channel controller for the legacy drives, a PCIe adaptor for NVMe. It is never put back in a server, and never in a controller that will try to rebuild. Drives that answer at full speed are imaged; drives with weak or failed heads go to the clean bench, where matched donors are fitted and the service area repaired before a sector is read.

Read at its native interfaceFailing heads to the clean bench

Imaged once, at its native sector size

Every drive is imaged sector by sector, head by head where it needs it, with the bad areas last. Drives with 520- or 528-byte sectors are imaged as they are and the extra bytes stripped from the image, never the drive. Self-encrypting drives are unlocked on the imager with the key you supply. From then on the originals are not touched again.

Head by head, weak areas lastNative sector size preserved

The image, and the set

Where the set is healthy and one member was the job, the image goes back to you on a fresh drive, sector-identical, ready to rebuild from. Where the set is the job, every member is imaged and the array reassembled in software from the images: order, chunk size, parity rotation and the reshape point read from the drives' own metadata, the file system repaired on the virtual volume, never on the originals. The array work is covered in full on our RAID array site, and it happens on the same bench.

One member: a sector-identical image on fresh mediaA set: reassembled in software from the images

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 job3–4 days at the bench

From the bench

One slot, once, server off. Hot-plugging a drive that may be failing into slot after slot is the same as power-cycling it.
Never on a desktop. A SAS drive will not connect; a SATA member will be offered for initialising and may be, by a helpful colleague.
Several at once is the host. Four drives that vanished in one second lost a cable, an expander or a supply, and are usually fine.
A drive that spins and is not seen is a firmware or head job. The bench brings it ready on its own terms.

One job, followed all the way through.

UK · RDD-2026-0565JOB LOGGED ✓

An HUH721212AL5200 out of an MD1400 that vanished from the shelf, tried in three slots and two servers over a weekend, and finally sent

The controller log, read from the export, showed the drive timing out for a fortnight before it vanished; the three slots and two servers had added a run of spin-ups to a drive whose service area was failing. On the bench the service area was repaired and the drive brought ready on the SAS imager, and it was imaged with its weak areas last. It came back complete, a little later and a little luckier than it needed to be.

100% of the member recovered5 days here, and back by post

Illustrative example — replace with a genuine case

What helps, and what harms.

Do this much first

Read the controller log and the carrier LED first
Try one known-good slot, once, with the server off
Power down and send the drive in its carrier
Tell us what it was detected as, if anything

What sets us back

Reseating it slot after slot
Trying it in another server or on a desktop
Power-cycling to see whether it appears
Initialising anything the host offers to

Questions answered before you commit.

My SAS drive is not detected. Has it failed?

Half the time it is the slot, the cable or the expander, and one move to a known-good slot with the server off settles it. If the controller log shows it failing before it vanished, it has failed, and the checks stop there.

The drive spins but the controller cannot see it. Is it dead?

Usually not. Its firmware or its heads will not bring it ready, and the bench brings it ready on its own terms. Do not keep trying.

Several drives disappeared at once. Are they all dead?

Almost certainly not. A cable, an expander, a backplane or a supply failed. The drives are usually fine.

What does it cost?

If it is the slot, nothing, and the free look costs nothing either. If it is the drive, £300 + VAT.

How long does it take?

3–4 days at the bench for one drive.

Where this usually leads.

Several drives failed at once →Drive shows 0 GB or incompatible sector size →SED drive locked →SAS 2.5-inch 10K and 15K →

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. Until that list reaches you, leave the server off and the drives in their slots.

0800 6890668

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