Message first
What it is saying, in the vendor's words, and the button to leave alone. The dialects differ. The first move does not.
Every controller says the same handful of things in its own dialect, and each dialect comes with a button that makes it worse. A PERC says Virtual disk degraded and Foreign configuration found, and offers Import and Clear. A Smart Array says Logical drive failed and, at POST, 1779 with F1 and F2. MegaRAID says Unconfigured bad and Offline and offers to force a drive online. mdadm says not enough devices and the forum offers --create. ZFS says insufficient replicas and offers -F. Storage Spaces says No redundancy and offers to reset the pool. Find yours below; each page quotes the vendor's own words, says what they mean, and names the button to leave alone. A set of two to four members is £500 + VAT upwards after the free look, fixed in writing, and on most jobs no data means no bill.
Rather talk it through? An engineer answers the bench line
0800 6890668
What the controller says, or what the software says.
Rather begin with the level →What the controller says
Virtual disk degradedPERC and MegaRAID: a member out, still readable, no margin. Image the weak drives before anything rebuilds→Virtual disk failed or offlineToo many members out. Every member imaged; the set reassembled from images with the first-dropped drive's stripes→Foreign configuration: import or clearMetadata the controller does not claim, and 'Virtual disk import failed'. Import only with every member present; never clear→HP 1779: replacement drive(s) detected'Select F2 to accept data loss.' Why neither F1 nor F2 is the answer until the members are imaged→HP 1785, 1789, 1793 and 1831Not configured, not responding, and write-back cache lost: HPE's advisories, quoted, and what each leaves on the drives→Preserved cache and cache data lostWrites the controller never finished. What discarding it does to the file system on top→Rebuild failed: a second drive went during itThe commonest way an array arrives. The first-dropped drive holds the stripes the rebuild never reached→What the software says
mdadm: not enough devices, array inactiveEvent counts, superblock versions, and the two commands the forum offers that write over the answer→ZFS pool FAULTED: insufficient replicasA vdev past its parity, or a member missing. Why zpool import -F belongs on images only→Storage Spaces: no redundancy, detachedMicrosoft's own definitions, the 2020 parity issue, and why chkdsk is the wrong move on a RAW space→vSAN: object inaccessible, reduced availabilityBroadcom's health states, the 60-minute repair timer, absent and degraded components→QNAP read-only, Synology crashedThe array-layer view of two NAS messages, and the link to the NAS site for the unit→The one rule under all of them.
Every message on this page means that the controller or the software has lost trust in some of the members, or has too few of them left to keep its promise. None of them means the data is gone. What loses the data is what happens next: a rebuild that reads every sector of survivors bought on the same day as the drive that failed, a foreign configuration cleared to make the warning go away, F2 pressed at a 1779 prompt, a stale drive forced online, a pool rewound with -F on the originals, a new array created over the old one and initialised, chkdsk run on a volume assembled with the wrong stripe.
So the first move is the same whatever the dialect. Export the log if it will still give one. Power down. Write the slot number on each drive before it comes out, and send every member, including the one that failed first. The bench images every drive on the equipment its interface needs, reads the geometry from the metadata or recovers it from the parity, assembles the set in software from the images and repairs the file system on a copy of the virtual volume. The pages above say the same thing in each vendor's own words, with the advisory numbers and dates where there are any, and the first-response page has the reasons in one place.
The questions that come up first.
The set is degraded but still working. Should I rebuild?
Only if every surviving member is healthy and you have a backup. If a second drive shows predictive failure, the rebuild reads the bad sectors that finish it. Copy what matters, power down, and image the weak drives first.
Should I import the foreign configuration?
Only if every member is present and the configuration is current on all of them. If a member is missing or one drive dropped out and came back, no. Clearing it is never the answer.
Should I press F1 or F2 at the HP 1779 prompt?
Neither, until the members have been imaged. F2 re-enables the logical drive on whatever the controller now sees, which HPE itself describes as accepting data loss; F1 leaves it disabled and buys time.
What does it cost?
A set of two to four members is £500 + VAT upwards; larger sets, 15K SAS sets, storage shelves and enterprise storage from £1,250 + VAT. Fixed in writing after the free look.
Not on the list?
Copy out what it says, or export the log, and send it with the form. An engineer places it faster than any menu, and asking is free.