RAID 5 image taken, but now unable to recover

[colossus]

Hi,

I'm having a problem trying to recover data from a RAID 5 set.

Previously the drive in question had a small amount of bad sectors, I have taken an image of this drive in ZAR as I did not want to put any more load on this HDD.

When using the drive direcly in ZAR, its able to recover data.

When using the image, ZAR errors out saying :

Performance: BuildSwitchList 3m 19s
Vote RAID stripe size: 128; Count=14050 ; separation 83.2%
Purged a total of 48474 known false positives (stripe size mismatched)
Remaining 21192 records
Vote Start offset: 0; Count=10704 ; separation 3.7%
RCRD/RSTR bias @3753
RAID: Test RAID0
Performance: Ident data query (9803 of 212461) 0s
Parity for disk 0200 at 0
Performance: Ident data query (11607 of 195875) 0s
Parity for disk 0500 at 3
Too low separation (1384 vs. 3707)
Final nonzero RAID layout scores
UNABLE TO CONTINUE:
Unable to reconstruct the RAID
Unable to continue processing, program will now terminate.
Not a bug - data is probably beyond repair, or something is misconfigured.



Ive taken an image several times and I'm sure theres nothing wrong with it. Is there any way to force ZAR not to simply die?

When ZAR is scanning it finds data on the drives and generates parity so I think its very close to recovering the data from this image.

Can you offer any help?


Thanks,

James.

[Alexey V. Gubin]

Try this -
In "Advanced Configuration",

under "RAID" section, clear "Enable RCRD bias"
under "Common filesystem analysis", make sure "Quick scan" is set to "Disabed"retry to see if this helps

[colossus]

Hi Alexey,

I have tried what you suggest but this still didnt work.

Is there any chance after the parity is generated that the program can force a file scan?

Thanks,


James.

[Alexey V. Gubin]

We still hoping to make it work as it is, due Monday most likely.

[colossus]

Thank you, I will look forward to a new release!

James.

[Alexey V. Gubin]

OK so here we go

1. Download and install http://www.z-a-recovery.com/zar-83-030.exe
2. Go to advanced configuration, and set "Quick scan" back to "Automatic" under "Common filesystem analysis".
3. Retry same as previously.

Should work this time. Unless some additional (unrelated) problem arises.

[colossus]

Thanks Alex,

I am trying this out now.

James.

[colossus]

Hi Alex,

It got past the raid parity but its been at this screen for 17hrs and hasnt moved an inch.

Imaged attached.


Last few lines of the log file:

Performance: BuildSwitchList 4m 28s
Vote RAID stripe size: 128; Count=14100 ; separation 83.4%
Purged a total of 48715 known false positives (stripe size mismatched)
Remaining 21301 records
Vote Start offset: 0; Count=10803 ; separation 4.4%
RCRD/RSTR bias @3798
RAID: Test RAID0
Performance: Ident data query (10850 of 195195) 0s
Parity for disk 0500 at 3
Performance: Ident data query (10284 of 216828) 0s
Parity for disk 0102 at 0
Performance: Ident data query (12490 of 195533) 0s
Parity for disk 0103 at 2
Performance: Ident data query (6788 of 207018) 0s
Parity for disk 0104 at 1
Filtered 5950 ghost entries
RAID: Test RAID5/Checkerboard
Vote Starting disk: 1280; Count=2568 ; separation 61.3%
Vote Next disk for 0500: 259; Count=1520 ; separation 99.9%
Vote Next disk for 0103: 260; Count=1529 ; separation 100.0%
Vote Next disk for 0104: 258; Count=1546 ; separation 100.0%
RAID: Test RAID5/LDM
Rotation parameters for array type RAID5 (Checkerboard) start 3 rotation 3
LDM rotation parameters mismatch
Final nonzero RAID layout scores
RAID5 (Checkerboard):93.87
Virtual RAID settings changed for Virtual RAID #1



Thanks.

[Alexey V. Gubin]

And how long it took to process the RAID (before it stalled)?

[colossus]

I left it going overnight, I looked at it after about 2-3 hours and I think it was around 20% or so.

I'm pretty sure this new version ran alot quicker then previous ones. Before it normally took 24hrs + to generate the parity and scan files. Now it does it in an evening.

Just out of curiosoty I have plugged in the old HDD with the bad sectors and ran ZAR again. It picked up the NTFS filesystem and all its files. I am just testing the recovery on a few files so I do not know what the recovered files are like yet.

It seems very odd that the image I created using ZAR / Zlon it has difficuilty with?

Thanks.

[Alexey V. Gubin]

It is not the image. It is an array which we have difficulty with. If it were physical devices, not images, it would end up the same. "Image" part works just fine.