R-Studio for RAID recovery

Discussions on using the professional data recovery program R-STUDIO for RAID re-construction, NAS recovery, and recovery of various disk and volume managers: Windows storage spaces, Apple volumes, and Linux Logical Volume Manager.
Hank

R-Studio for RAID recovery

Post by Hank » Mon Dec 08, 2008 11:59 pm

Hello. Here's my situation. I was running RAID 0+1 (4 disks striped & mirrored) and had a drive fail (confirmed it was dead). Shortly after that a second drive failed (or at least the RAID suddenly was broken). I ran the manufacturer's diagnostic tools on the three drives, but no problems were found. It wasn't until later that I learned this kind of diagnostic software is known to write data to the drives it inspects! So it's possible some data was written to these drives, further damaging RAID parity. So I'm left with three drives: the two good drives which were mirrors of each other, and the one problem drive that contained the other half of the RAID, but likely has some bad sectors, and may have had some additional data written to it. I have since installed Vista on the redundant drive and am now concentrating on recovering the RAID from the two remaining drives (treating them as RAID-0).

I have tried a number of different RAID recovery software, and have had varying degrees of success, but can't seem to fully recover the RAID. Using R-Studio, I can "virtually" reconstruct the RAID, and it shows me the file directories intact, as well as the file names, but when I retrieve individual files, like a JPEG, they are all corrupt to some extent - only half the file displays, or it won't display at all.

Other recovery software seems to have issues scanning the second drive. It will get about a third of the way through scanning and then run into errors (I'm assuming bad sectors?).

The data is not critical enough to pay someone to retrieve it. I'm getting close to throwing in the towel, but the fact that I can see the file directories intact, and preview partial files gives me hope. It seems like I'm so close! So I'm looking for some insight and suggestions.

Is it a question of tweaking the RAID recovery parameters until I find the magic combination?
Should I consider trying to fix the problem sectors on the bad drive, or will that only further disrupt the parity?

Any help would be appreciated.

Alt
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Re: R-Studio for RAID recovery

Post by Alt » Tue Dec 09, 2008 9:00 am

I can explain you the mystery of an apparently valid data structure (the folder tree and file names) and failure to recover the actual files. The problem is that the data describing the data structure reside on the first (and operational) disk and maybe partially on the good part of the second drive, whereas the data of the files reside partially on the good first disk and partially on the faulty second one. That is why you have half picture good, half picture bad. And that draws me to the conclusion that chances to recover data are grim in your case.
Although you may keep trying and find the files that reside on the good part of the second disk. I recommend you to make an image of the second disk and work with it, although that would require another disk, larger than the second one.
I think the only RAID parameter you may tweak with is Block size. You should specify it correctly.

Hank

Re: R-Studio for RAID recovery

Post by Hank » Tue Dec 09, 2008 9:32 am

Hi. Thanks for the quick response.
Is there any way to fix the problem sectors of the bad drive without further disrupting the parity?
Is there any way to make a compressed image of the disk to save space (it's a 1 TB drive)?

Alt
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Re: R-Studio for RAID recovery

Post by Alt » Tue Dec 09, 2008 12:51 pm

0!!! Make the image BEFORE you do anything with the bad sectors.
1. I don't think you can do anything with the problem sectors that won't put the data integrity further on risk.
2. Yes you can. Select the drive in the left pane -> Menu Drive -> Create Image -> Compressed Image (R-Drive Image compatible). Specify Image compression ratio. The more to the right, the smaller size. Below Estimated size will show you the possible size of the image. Please note that this is a very rough estimation, and the lesser image is, the slower R-Studio will work with it.
You may also play with the pattern to fill bad sectors on the Bad Sectors tab. Please note that increasing the Read attempts parameter (default 1) will unlikely help you to read the bad sectors correctly.

Hank

Re: R-Studio for RAID recovery

Post by Hank » Sat Mar 07, 2009 7:10 pm

Hi. I'm just getting around to making an image of the bad 1 TB drive, which I'm saving to an empty 1 TB drive. When I try using the Compressed Image option, the size comes up as 931.5 GB, and doesn't change when I move the slider around. When I hit OK, I get an error "Cannot create image file. Insufficient disk space." Am I doing something wrong?

Alt
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Re: R-Studio for RAID recovery

Post by Alt » Mon Mar 09, 2009 5:11 am

For the test purpose: can you create a plain image? Or R-Studio says not enough space?
Don't create an actual image, just select this option.
If your disk contains a lot of already compressed archives, R-Studio cannot compress the disk further.

Hank

Re: R-Studio for RAID recovery

Post by Hank » Tue Mar 10, 2009 12:11 am

I tried making a plain image as you suggested, and yes, R-Studio says not enough space.
However, as another test, I placed a single JPEG file on the blank 1 TB Drive, and then tried making an image of that drive, and I still have the exact same problem: When I try using the Compressed Image option, the size comes up as 931.5 GB, and doesn't change when I move the slider around. When I hit OK, I get an error "Cannot create image file. Insufficient disk space." Just to confirm, under "Image Split Size" I have "Automatic" checked. Would I be better off choosing "Fixed"?

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