Devices · arrays and servers
Before you do anything, switch off the server. Most arrays are not finished off by their first fault; it is usually the reaction: a rebuild asking a worn member for one fault-free pass from start to end, a drive the card refused pushed back into its slot, drives moved around in hope. Mirrors tend to flatter their owners too. Two disks bought on the same date, installed on the same afternoon and run equally hard will generally wear out at roughly the same time. Sets come to us from a 3PL office on Markham Vale and an accountancy practice in West Bridgford, Nottingham. Work on an array or server starts at £500 + VAT, the look that sets the price is free, and nothing degrades any further here, because all operations are performed on images.
Ask an engineer and the first look is free
0115 8220606
| What is happening | What usually causes it | What that means for you |
|---|---|---|
| Foreign Configuration Found — on a Dell PERC | The drives describe a set the controller knows nothing about | Answer nothing at all. Every member gets imaged. |
| 1786 on an HP: Drive Array Recovery Needed | Redundancy has gone, and a rebuild is queued or in progress | Take it off power, then image the entire set |
| 1784 on an HP: Drive Array Drive Failure | One member of the set has stopped | Putting a new disk in will not mend it |
| 1787 on an HP: Drive Array Operating in Interim Recovery Mode | A member has failed and the set is operating in degraded mode | Stop. Take images of all members before replacing any. |
| 1788 on an HP: Drive Array Reports Incorrect Drive Replacement | Somebody has put the disks back out of order | Stop there. Bay order settles everything. |
| Virtual Drive: Degraded, or Offline | Parity has gone, or the whole volume has | Get the server off power altogether |
| 1720 on an HP: SMART drive detects imminent failure | A disk that is still a member of the set reports its own failure | Get it imaged that same day |
Your case number is assigned when the item is received. Then an engineer works out what went wrong (no charge). At this point, you receive a basic summary of which parts are recoverable and which are not. You also receive a single written quote for the price of the recovery. Accept the quoted price or turn it down, and there is no obligation to pay anything.
Hardware built to image failing disks makes copies of all members, including the rejected ones. Once the copies are made, the job exists solely on them. The originals are read but never written to.
Metadata on the members gives three pieces of information: which disk sat in which slot, the size of the stripe, and which way the parity rotates. The set is then rebuilt in software, on our own equipment, from the images. Your controller plays no part, and no drive is ever allowed to rebuild.
Then the file system is repaired on the rebuilt copy, and the virtual-machine containers and database stores are opened up. You check the file list against what you expected to see, and nothing ships until you have.
A complete file list will be provided before any invoicing. Simply say "yes" or "no" to what we found: yes means it is billed, no means it is not, and in most cases you only pay if we recover your data. What we find is posted to you on media purchased specifically for your case, at no additional cost to you. We consider the process complete once you have opened those files yourself on your own computer.
Why single parity ran out of headroom: manufacturers quote one unreadable sector per 1014 bits for a consumer SATA disk, roughly one bad sector in every 12.5TB read back. When rebuilding a large single-parity set, each surviving member must deliver many times that amount in one clean pass. That is when such rebuilds stop working. The numbers are the makers' own, and how well they hold for real disks is still debated.
Friday's rebuild was halfway through when a second member dropped out, and the live volume could no longer be mounted. Power off. Hands off. Each disk was then imaged onto our own storage; three of the images came back sound, and the stripe was rebuilt from those three, plus whatever the fourth would still give up. Monday's shift ran as usual.
Yes. Whichever disk was kicked out may have the latest copy of some stripes, so it travels with the rest. Every block is then read from whichever disk gives it up most cleanly.
Not really. Where each disk sat, the stripe size and the direction parity turns are all recorded on the disks. Getting that off them is analysis, not guessing. Number them anyway if you can; an hour saved is worth having.
Both come back. Once the set is assembled again, VMDK and VHDX containers and databases are extracted and mounted here one by one for review, since a filename in a listing tells you nothing about the state of its contents.
Typically four to seven working days where several disks are involved. If trading has genuinely stopped, let us know: your position in our queue changes, and intake is booked around the date you must meet.
The look costs nothing. It gives you a file listing of what opened and what did not, along with the cost of finishing the job, in writing, before anything chargeable begins. In most cases you only pay if we recover your data. Do not switch the drive on until you have that listing.