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apple raid missing disk

Hello,



i have apple raid concatenated JBOD 4 disks storage, without redundancy, everything was working normal when the power goes down and did not come back to mount the raid unit, the hard disks are working perfectly without problems, it is only logical problem of the raid partition that has lost a slice and does not mount more, I have personal files like photos that I do not have backup, who can help me giving tips on how to recover and ride this raid again I will be very grateful.


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Mac mini, iOS 11.0.3, null

Posted on Oct 12, 2017 6:48 AM

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Oct 19, 2017 6:08 PM in response to MrHoffman

thank you very much for the time spent trying to help User uploaded fileMrHoffman and User uploaded fileGrant Bennet-Alder I´m still searching to see if I can solve this problem, I did several tests on hd that theoretically lost the partition, it is 100% functional, it is a logical problem, thank you and I keep trying to get more help.

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Oct 12, 2017 1:21 PM in response to leocostadj

An Apple concatenated disk set means the disks are accreted together, without any data redundancy, and without any of the performance benefits of RAID 0 when that's used with traditional hard disks.


(RAID 0 means disk striping means similar-sized hunks of the data are scattered across all of the disks with no redundancy. Neither of these approaches are particularly recoverable on hardware failures, unfortunately. RAID 1, RAID 5, RAID 6 and RAID 10 all replicate the data, and will usually permit data recovery after a disk failure.)


With concatenated disks, if there's no backup and if there's no Time Machine, and if powering down the whole configuration and re-seating the failed drive into the bay and powering it all up and trying again doesn't allow access, then you're headed toward acquiring a tool such as DiskWarrior or analogous, or consider contacting a data recovery firm directly to see what they offer and whether they can read and rebuild from the array.


Recovery services will generally require a fee paid, irrespective of whether they're able to recover any data.

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Oct 12, 2017 3:50 PM in response to leocostadj

panic moves you could try now, before giving up and doing what MrHoffman says, include:


selecting that wandering drive and running repair disk on it. Repeat until it comes clean or gets hopelessly stuck. If it comes clean, use the "mount" button is disk Utility to mount it, then see if the RAID will accept it back, or what status it gets.

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Oct 12, 2017 4:54 PM in response to Grant Bennet-Alder

Grant Bennet-Alder wrote:


panic moves you could try now, before giving up and doing what MrHoffman says, include:


selecting that wandering drive and running repair disk on it. Repeat until it comes clean or gets hopelessly stuck. If it comes clean, use the "mount" button is disk Utility to mount it, then see if the RAID will accept it back, or what status it gets.


I'm hesitant to recommend sending a whole lot of I/O at a sketchy or failing hard disk drive, as I'd rather (try to) leave the last few "gasps" for the recovery service to try to use during data recovery, rather than finishing off whatever might be failing within the drive with what may be a futile effort to repair it. If it reads at all and if I were inclined to send a fair amount of I/O at a hard disk, I'd tend to try to do a dd-style disk image first, to try to capture whatever data was still readable, while it was still readable. Hard disks don't always degrade evenly or even gracefully, though once they start going visibly weird they're usually pretty far toward gone.

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Oct 12, 2017 6:11 PM in response to MrHoffman

Excellent point, MrHoffman!


My direct "school of hard knocks" experience with Apple RAID is only with Mirrored RAID. I had an instance where one disk dropped out, and it appeared that at the first sign of a Bad Block, it broke the RAID and the errant drive wandered off. I repaired that Bad Block problem once, rebuilt the mirrored RAID from the good drive, and went on with it.


So the on topic part of my story is:

that at the first sign of trouble, the RAID seems to split (at least that is what the mirrored RAID did.) There may still be enough life in it to copy most stuff off.


... back to my "story" and what else I learned:

Then that same RAID drive developed another bad block shortly thereafter. I was not happy about it breaking my RAID again, but while stewing about it I realized that was EXACTLY the behavior I wanted. If the drive had the slightest problem, it was no longer good enough to hold my precious data, and needed to be replaced with a drive that worked absolutely perfectly.


Your suggestions that backups are still needed, even with Mirroring, rings true here.

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Oct 13, 2017 1:50 AM in response to MrHoffman

all 4 hard disk 8tb are working perfectly, are new, what happened was lack of power and the raid does not mount anymore, I tried to recover the diskwarrior but the unit does not appear, I rode rstudio mounting the missing disk, mounted a similar raid but in data recovery fails 25% which is exactly the missing disk, I'm going to consider your tip to take in a data recovery company, thank you for responding and trying to help.

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Oct 13, 2017 4:12 AM in response to leocostadj

Sorry for the post repeated, gave some problem here at the time of reply, I thought of making a picture of this hd with the DD to another hard disk and remove from the raid and insert again, my question would be if when to include in the raid, will it be formatted? the autorebuild works on the other raid like raid1, does it work as concatenated jbod?

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Oct 13, 2017 4:21 AM in response to leocostadj

I'm thinking of giving some command to remove and reinsert the disk that gave error with commands in the terminal:


diskutil appleraid remove 66E9EDE0-5F1D-4656-990D-CFEA511F252E disk7S2


diskutil addtoRAID member disk7S2 66E9EDE0-5F1D-4656-990D-CFEA511F252E


and diskutil checkraid


Will it work? When you insert the hard disk again will it format this drive? Can you ride the raid?

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Oct 13, 2017 8:44 AM in response to leocostadj

Do not apply those Terminal commands, they are not appropriate for your situation. There is no copy of that data. Rebuild commands can only do something for MIRRORED RAID, where there is a complete duplicate copy on the other drive that is still working and Mounted.


Some users have reported success with Data Rescue from Prosoft, which has a free trial period (where you can evaluate what it might do for you before you purchase it.) Data Rescue requires a different drive to save the rescued files, but may be able to reach onto an unmountable drive and grab some files.

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Oct 13, 2017 9:49 AM in response to leocostadj

FWIW, there's no such thing as a flawless hard disk drive, immediate and newly-deployed failures are common, some number of drives will age out and fail over the average lifetime of the devices, and failures secondary to power glitches are common and whether due to surge or brownout or a generic blown capacitor, and hard disk drives from the same production batch can share the same sorts of design or firmware or specific-batches-of-parts-related flaws...


For hardware RAID, RAID-1 or RAID-6 or RAID-10 or equivalent are preferred.


I prefer to avoid RAID-1, RAID-5 and concatenated.


Whatever is in use, with backups. With off-site backups, if the data is sufficiently valuable.


Stuff always and still will fail, backups will sometimes be unreadable, unfortunately.


Murphy was an optimist.

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Oct 13, 2017 9:53 AM in response to leocostadj

leocostadj wrote:


Will it work? When you insert the hard disk again will it format this drive? Can you ride the raid?


As Grant Bennet-Alder indicates... Those appleraid commands are not associated with the concatenated volumes in use here. Those commands will not have the desired result here.


I'd further be cautious around whether using appleraid commands might have the side-effect of overwriting some of the existing data still available, too.

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Oct 20, 2017 7:58 PM in response to leocostadj

If you believe the drive is not "near death", there were several suggestions early on in this thread that were possibly appropriate, but were discouraged, because they could push a shaky drive over the edge.


You might want to revisit some of those suggestions in light of what you now believe is happening to the drive.

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apple raid missing disk

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