RDD / Whatever it is saying now / Foreign configuration found

PERC · MegaRAID · Foreign configuration · Import · Clear · controller replaced

Foreign configuration found. The drives are describing a set the controller does not recognise. Clearing it makes them stop.

Every drive in a hardware RAID set carries a copy of the set's description: which array it belongs to, its position, the RAID level, the stripe size, and a count of how current its copy is. A controller that boots and finds drives whose description does not match its own records, or that has no records at all because it is a replacement, reports a foreign configuration and offers two buttons. Import adopts the description and brings the set up. Clear deletes the description from the drives so that they can be presented as new. The wrong button at three in the morning is the commonest way a recoverable set becomes a reconstruction. One member imaged is £300 + VAT after the free look, fixed in writing; a set whose configuration was cleared is reassembled from images and priced as a set.

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

Do not clear the foreign configuration. It deletes the set's description from the drives. Do not import it unless every member is present and nothing was written since the set was last consistent. Power down, label the slots, and photograph the controller's screen.

What a foreign configuration is, and what each button does.

Hardware RAID controllers write their configuration to a reserved area at the end of every member drive, the DDF or a vendor format, so that a set can survive its controller. When a PERC or a MegaRAID starts, it reads the description from every drive and compares it with the last configuration it saved. Drives whose description matches are brought up; drives whose description belongs to a set the controller does not remember are reported as foreign, and the controller waits to be told what to do.

The usual reasons are innocent. The controller was replaced and remembers nothing. The drives were moved to another server, or between slots. A drive dropped out during a power cut and came back with an older description than the others, so it disagrees with its own set. In every one of those cases the description on the drives is still the truth about the set, and Import reads it and brings the array up, provided every member is present and the copies agree. When a member is missing, or the copies disagree because one is stale, Import can bring up a set with the wrong geometry or the wrong member, and write to it.

Clear does one thing: it erases the description from the drives. The controller then sees unconfigured drives, and the next step, creating a new virtual disk on them, initialises them. The data is still on the platters until the initialise runs, but the description of how it was arranged is gone, and the bench has to reconstruct the geometry from the data itself. That is possible, and it is a longer job than reading a description that was there five minutes ago.

What it says, and what it means.

Describe yours to us →

What you see	The usual reason	Where that leaves you
Foreign configuration found after a controller swap	The new controller has no records	Import if every member is present and current; otherwise send the set
Foreign configuration on one drive of a running set	That drive dropped out and came back stale	Do not import it into the set; image it
Foreign configuration after drives were moved	The slots changed; the description did not	Import usually safe with all members present
Foreign configuration with a member missing	The description names a drive the controller cannot see	Do not import; find the drive or send the set
Configuration cleared already	The description is gone	Every member imaged; geometry reconstructed from the data

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 set that arrives with its foreign configuration intact is read on the bench from the description on the drives: order, level, stripe size and the event counts that say which member is current. A set whose configuration was cleared is read from the data itself, with the parity arithmetic used to find the order and stripe size.

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

Photograph the screen before you touch either button. The controller lists which drives are foreign and why, and the bench can read it from the photograph.
Import with a member missing brings up a degraded set that the controller will then want to rebuild. It is not safer than sending the set.
A cleared configuration is not a wiped drive. The data is still there; the description of its layout is not. It is reconstructed from the data.
Send the controller if it was the one that was replaced; its saved configuration, if any, is the other copy of the description.

One job, followed all the way through.

UK · RDD-2026-0562JOB LOGGED ✓

An R720 whose PERC H710 was replaced by an engineer who cleared the foreign configuration to get the new card to boot

Four drives arrived with their description erased and their data untouched. Each was imaged, and the RAID 5's order and stripe size were recovered from the parity arithmetic across the images; the set was reassembled in software and the NTFS volume mounted from the virtual array. Everything came back, a few days later than it needed to.

100% of the volume recovered8 days here, and back by post

Illustrative example — replace with a genuine case

What helps, and what harms.

Do this much first

Photograph the controller's screen
Power down and label the slots
Send every member, and the old controller if it was replaced
Tell us which drive was moved, swapped or replaced, and when

What sets us back

Clearing the foreign configuration
Importing it with a member missing
Creating a new virtual disk on the drives
Moving drives between slots to see

Questions answered before you commit.

Should I import the foreign configuration?

If every member is present, the copies agree and nothing has been written since the set was last consistent, yes. If a member is missing, or one drive dropped and came back, no.

I cleared it. Is the data gone?

Not yet. Clearing erases the description of the set, not the data. The set is reassembled from images with the geometry recovered from the data itself. Do not create a new virtual disk on the drives.

Why does one drive show foreign on a working set?

It dropped out and came back with an older description. Do not import it; image it, and let the set rebuild onto fresh media.

What does it cost?

£300 + VAT for one drive after the free look; a set whose configuration was cleared is imaged and reassembled from £500 + VAT for two to four members.

How long does it take?

5–10 days at the bench for a set; longer where the geometry must be reconstructed, and the figure says which.

Where this usually leads.

PERC virtual disk degraded or failed →Dell PowerEdge and PERC →Several drives failed at once →

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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Whatever it is saying now

What it costs, and what follows