RAID5 - Reverse RAID Required?

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.
rexyboy
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RAID5 - Reverse RAID Required?

Post by rexyboy » Sat Dec 15, 2018 5:43 am

Hi,
I am in the process of trying to recover files from my 5 disk RAID5 array. The drives come from a QNAP NAS which is having a problem with more than one drive. Yesterday I managed to assemble a Virtual Block RAID array using the disks based on data from ReclaiMe. I could see pretty much the entire folder structure and managed to grab some files as a test.

Today one of the drives is about to fall over if it hasn't already. I have taken the drive out of the array and added a Missing disk. I guessed this is where I should Reverse RAID the missing disk then probably perform the complete scan all over again. However, I am having a few challenges in getting it to work and understand the doc's. First question is; do I need to do an reverse raid and create an image of the missing disk or just continue with one less disk?

Secondly, the docs (Reverse RAID of RAID) seem to indicate that after the array is assembled with a missing disk in the right place you right click on Virtual Block RAID in the left hand panel and select 'Create Reverse RAID'. I find that this is shadowed out. Do I need to perform a scan first ? If I start the scan then select the partition below the disk I can do a 'Create Reverse RAID' on that but it seems at the wrong level.

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Any help on this would be greatly appreciated.
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Alt
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Re: RAID5 - Reverse RAID Required?

Post by Alt » Sun Dec 16, 2018 3:58 pm

rexyboy wrote:
Sat Dec 15, 2018 5:43 am
First question is; do I need to do an reverse raid and create an image of the missing disk or just continue with one less disk?
A RAID5 allows for one disk to fail. If only one disk in your setup has failed, a missing disk is enough. I'd strongly recommend you to create the images of all the disks, as if one more disk fails, the RAID5 cannot not be properly processed.
rexyboy wrote:
Sat Dec 15, 2018 5:43 am
after the array is assembled with a missing disk in the right place you right click on Virtual Block RAID in the left hand panel and select 'Create Reverse RAID'. I find that this is shadowed out. Do I need to perform a scan first ? If I start the scan then select the partition below the disk I can do a 'Create Reverse RAID' on that but it seems at the wrong level.
Assuming that you make a right-click at the right level, I cannot say why it is grayed out without thoughtful inspection. Maybe, data on other disks is corrupt? I'm not sure scan of the array will help.

rexyboy
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Re: RAID5 - Reverse RAID Required?

Post by rexyboy » Sun Dec 16, 2018 4:15 pm

One thought I had was that I need to do a scan before it will let the 'reverse raid' the disk level. Does anyone know if this is required?

From the first screen shot I included you can see what I right clicked on. I think this is the right level.

When I did the scan the first time I was able to get the majority of the structure and files without red crosses besides and successfully grabbed some test files so imagine the structure is broadly ok.

Any help would be appreciated.

Alt
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Re: RAID5 - Reverse RAID Required?

Post by Alt » Mon Dec 17, 2018 5:52 am

rexyboy wrote:
Sun Dec 16, 2018 4:15 pm
One thought I had was that I need to do a scan before it will let the 'reverse raid' the disk level. Does anyone know if this is required?
No, it isn't. Scan discovers file systems on the RAID, whereas the "reverse RAID" operations are a level below than that.
rexyboy wrote:
Sun Dec 16, 2018 4:15 pm
When I did the scan the first time I was able to get the majority of the structure and files without red crosses besides and successfully grabbed some test files so imagine the structure is broadly ok.
Did you do the second scan? If yes, what happened between the two? Possible another disk failure?

Data-Medics
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Re: RAID5 - Reverse RAID Required?

Post by Data-Medics » Mon Dec 17, 2018 3:13 pm

rexyboy wrote:
Sun Dec 16, 2018 4:15 pm
Any help would be appreciated.
A bit of advice. You should never go near a failing drive with data recovery software until you have a 100% sector by sector clone of the drive. What you are doing is a great way to permanently lose all the data on the array.

We don't even connect an assumed healthy drive to a computer without first cloning it entirely. You should always be working from clones, NEVER FROM ORIGINAL DRIVES!!!

rexyboy
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Re: RAID5 - Reverse RAID Required?

Post by rexyboy » Mon Dec 17, 2018 4:39 pm

The advice re cloning the failing drive before commencing is obviously solid.

A bit of a summary of the scans:

Scan 1: All 5 of the 5 disk array present. One of the disks had errors. Most of the file system was available. I think some of the items with red crosses were actually deleted files etc that are not required. Possibly all data present.

Scan 2: removed the damaged drive completely from the computer. Running 4 of 5 disks in the array. No errors thrown during scan. SMART stats all good. The scan is taking a little longer than the first scan. I have done the scan and now waiting for 'Open Drive Files' which seems to take about the same time as the scan.

BTW: Is there a way to save the "Open Drive Files' step so that you can just load that up as it takes about 24 hours each time even if I have saved the scan (.scn) file?

Thanks

Data-Medics
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Re: RAID5 - Reverse RAID Required?

Post by Data-Medics » Tue Dec 18, 2018 4:08 pm

rexyboy wrote:
Mon Dec 17, 2018 4:39 pm
BTW: Is there a way to save the "Open Drive Files' step so that you can just load that up as it takes about 24 hours each time even if I have saved the scan (.scn) file?
No, there isn't. But having a 16 core processor and 64Gb+ of RAM really does help speed that process up. It also helps if you clone all the drives to image files on a couple of high-speed RAID arrays directly connected to the workstation. Having DAS that can read 700+Mb/s makes everything faster. Otherwise, these RAID recoveries can take forever.

But, if you're not doing this professionally and it's a one-off case, it probably isn't worth that sort of investment.

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