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Old August 6, 2013, 09:27 AM
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Default RAID 5 data recovery?

What's the best way to attempt data recovery on a RAID5 where 2/3 drives have failed? Keeping in mind that this is for extended family that would have to ship me the drives. Is there a way to 'rebuild' the failed RAID in a new system, then attempt recovery?
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Old August 6, 2013, 10:59 AM
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No experience with RAID but given that 2/3 drives are dead, it may not be possible to recover. Did a quick Google search and here's what I found that may be useful:

Recovering data from a RAID 5 array with two disks dead | Gamers With Jobs

data loss - 2 drives "failed" on a 3 drive RAID 5 - Server Fault
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Old August 6, 2013, 11:27 AM
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if the 2 of 3 drives are actually dead, chances of recovering anything are pretty much none

If you read the first link moocow posted, it describes a scenario such as follows, though the post in that link, was a really bad user error, and luckily there was no actual failed drives

if the drives were forced out of the array due to errors, which will happen when using consumers drivers without TLR because they'll hit a bad sector and continue trying to recover, when the controller gets no response, it kicks them off. in this case, the data should be mostly safe. you might be able to force the array to make the drives active again and as long as they don't continue to error out, you should be able to back up the data and then attempt to rebuild the array

if you can't force the drives back into the array, there is software, noted in one of the above links, raid reconstructor, which can rebuild an image from the drives for you to mount with other software and recover data from. the issue here is that you require space large enough to store the image which will be the combined size of the drives it was on. you also need to know the block size used in the array, guessing doesn't work. and you may need other details of how the array was setup, without those, trial and error will take a long, long, long, extremely long time. Also, non hardware-raid arrays (IE software assisted raid, such as your onboard intel) don't exactly follow typical standards, so recovering those with this method, aren't always that easy, if you get anywhere

There's a reason I don't use RAID5, single parity is just not enough
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Old August 6, 2013, 02:16 PM
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Not much to add to the above. Other than a recommendation to move from RAID 5 to RAID 6, 10 or 50 (if you can justify the cost).

You DO have backups? :-p
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Old August 6, 2013, 03:25 PM
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They have a backup from a couple months ago. Unfortunately it's for a home business, so they're learning a hard lesson. Going to try to get them to RAID 10 for the future, along with a cloud backup option. But for now, I'll try to rebuild the RAID when the drives arrive, but not sure what I'll get.
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Old August 6, 2013, 04:01 PM
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I've had some success in the past with this software: RAID Recovery for Windows - RAID arrays - Hardware and software RAIDs - Data Recovery Software Products

It was RAID0 though and both drives were still functional, just the array itself had become corrupted and was no longer recognized by the SATA chipset as being RAID.

If the drives are physically broken/dead, I don't think there's any hope in getting much data back.
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Old August 6, 2013, 04:06 PM
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A bit off topic, but whatever happened to the proprietary 0+1 raid setups I remember seeing? IIRC you'd basically have a multiple HDD speed setup (raid 0) with no redundancy, but then that array in it's totality would be mirrored (raid 1) onto a single drive of the same size as the total raid 0 array.
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Old August 6, 2013, 07:17 PM
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I used to have a R5 setup, what a "P.I.A" rebuilding. Hopefully you just have to re-initiate the drives and rebuild but if 2 drives have actually failed I think your friends are "S.O.L"
I'm guessing this was a software raid setup. If so I think I seen somewhere that you will need either the same mobo or same raid software version (amd or intel) or possibly both before anything will try to rebuild. Check into this they may need to also send the mobo or the raid card if that's the case.
Good Luck!!
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Old August 6, 2013, 08:30 PM
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talk to grinder about this... he has extensive experience with failed raids this year due to massive corrosion problems on the hardware. Just because a drive is "dead" doesn't mean the data isn't still on there. You can send the entire raid array (I believe) to the men in white coats and recover all the data. It really comes down to how important the data is and how much money the affected parties want to spend.

Just because you have a raid 5 doesn't mean data shouldn't be backed up...
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Old August 6, 2013, 09:48 PM
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stlouis1 pretty much nailed it. Intimate knowledge of the RAID setup and a detailed log of what drive failed and when will put you at a tactical advantage for attempting a rebuild of the array. Know the drive port positions, what drive failed first and why, what drive failed last and why. Know if the failed drives are actually degrading into a worse state (they may not last the days it takes to reconstruct the array with software).

White lab coat guys can cost south of $10k to recover your data.

My standard is typically RAID 5 + hot spare... coupled with a tough as nails backup regime you can't go wrong. I've had a raid10 array that was actually more fragile than a RAID5 on a quality adapter card. can't knock that!
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