Devices · arrays and server storage
It is seldom the first fault that finishes an array. What finishes it is what comes next — a rebuild demanding one faultless end-to-end read from a worn-out member until it quits, a rejected disk pushed back into its bay, drives moved around on the chance that helps. Mirroring is worth less than people assume: the two halves went into their bays on one afternoon and have accumulated identical hours since. Sets arrive from a Plymouth office at Sutton Harbour, from a boatyard on the Cattewater, from an engineering shop outside Camborne. Everything runs on images, so nothing deteriorates once it is here.
You will be talking to an engineer
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| What shows up | What that points to | What to do |
|---|---|---|
| Foreign Configuration Found (Dell PERC) | The drives describe a set the card cannot identify | Answer none of it. Image each member. |
| 1786 — Drive Array Recovery Needed (HP) | Redundancy is gone, with a rebuild queued or partly done | Shut it down and image the set |
| 1784 — Drive Array Drive Failure (HP) | A member of the set has died | Fitting a new disk will not resolve it |
| 1788 — Improper Drive Replacement (HP) | The drives went back in the wrong sequence | Halt. Bay order decides it. |
| Virtual Drive is Degraded / Offline | The volume has lost its parity, or has gone entirely | Take the server fully off |
| 1720 — SMART drive detects imminent failure (HP) | A disk still in the array is warning it will fail | Get it imaged that day |
Whatever arrives is booked in under a case number on the day it reaches the bench. An engineer then works out the actual fault, and that part is free. You get a plain answer on what can come off the drive and what cannot, followed by one price in writing. Nothing further happens until you have read it and agreed.
Every drive goes onto purpose-built imaging hardware, the ones the card had already rejected included. From that point everything runs on the copies. Not a byte goes back to what you sent us.
The layout itself yields the order the disks ran in, the stripe size and the way parity moves round. The set is then raised over the images on our own equipment. The card you sent is never used, and nothing at any point is instructed to rebuild.
Once the array is up the file system gets repaired, and the virtual-machine containers and databases follow it. A full listing is reconciled with the lot before any of it goes out.
Thinking it over costs you nothing. Everything the drive gave up is listed for you before any invoice exists, and the bill only follows your go-ahead. Files travel back on media bought in for your job, with return carriage paid at this end, and the case stays on the bench until you confirm they open on your own computer.
Where single parity got its name: makers specify a consumer SATA drive at a single unreadable sector for every 1014 bits, which comes to roughly one in each 12.5TB pulled off the disk. Rebuilding a large single-parity set asks a great deal more than that of every disk still standing, with no stumble anywhere, and that is where rebuilds fail. That figure comes from the manufacturers rather than from us, and its real-world weight is still argued over.
On the Friday a second member dropped out mid-rebuild, and the live volume stopped being readable. The array was switched off and left that way. Each of the four disks was imaged onto our own hardware, and the stripe was read back from three sound copies plus what little the fourth would still hand over. The Monday shift started on time.
Include it. A drive the controller threw out will often be holding the freshest copy of particular stripes, and every block gets taken from whichever member yielded it most cleanly.
It is not. Where each disk sat, how large the stripe is, and the order in which parity moves round are all derivable from what is written on the drives themselves. That is analysis at the bench, not a guess.
Both. Once the array stands, VMDK and VHDX containers come off first along with any database stores. Each of those is then mounted and opened here, because a name on a listing proves nothing by itself.
Reckon on four to seven working days where several disks are involved. Where trading has genuinely halted, tell us on the phone. The job moves up the queue and we arrange the intake around the date you need.
The diagnosis is free, and it comes back as a list: which files read, which do not, and what getting them off would take. Until then, leave the drive unplugged.