Recovery of Linux Software Raid Level 6

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.
lawern
Posts: 2
Joined: Fri Feb 25, 2011 6:02 am

Recovery of Linux Software Raid Level 6

Post by lawern » Fri Feb 25, 2011 6:24 am

Hi

I have a linux software RAID 6 with 6 disks from which I would like to recover data.
The RAID was created under Debian Linux with mdadm.
With 4 images of the disks I have tried to recover data.
The file system structure was identified by R-Studio, bu the restored files contain incorrect data.

I have build the RAID with the following parameters:

RAID type: RAID6 / Reed-Solomon
Block size: 64 KB
Block order: Left Synchronous (Standard)
Number of rows: 6

Are these parameters correct?

In the following the "mdadm --examine" output from one auf the RAID disks:
--
Magic : a92b4efc
Version : 00.90.00
UUID : 45943656:52f05e6d:fd473109:0414a25b (local to host cheops.hosts.kassel.intranet.agentes.de)
Creation Time : Thu Nov 4 14:56:30 2010
Raid Level : raid6
Used Dev Size : 1945294720 (1855.18 GiB 1991.98 GB)
Array Size : 7781178880 (7420.71 GiB 7967.93 GB)
Raid Devices : 6
Total Devices : 6
Preferred Minor : 3

Update Time : Thu Jan 6 12:06:44 2011
State : clean
Active Devices : 6
Working Devices : 6
Failed Devices : 0
Spare Devices : 0
Checksum : 512c8dca - correct
Events : 1724280

Chunk Size : 64K

Number Major Minor RaidDevice State
this 4 8 84 4 active sync /dev/sdf4

0 0 8 4 0 active sync /dev/sda4
1 1 8 36 1 active sync /dev/sdc4
2 2 8 52 2 active sync /dev/sdd4
3 3 8 68 3 active sync /dev/sde4
4 4 8 84 4 active sync /dev/sdf4
5 5 8 20 5 active sync /dev/sdb4
--

Thanks

Lars

Alt
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Re: Recovery of Linux Software Raid Level 6

Post by Alt » Mon Feb 28, 2011 6:54 am

Did you substitute the missing 2 disks with the Missing disk objects?

lawern
Posts: 2
Joined: Fri Feb 25, 2011 6:02 am

Re: Recovery of Linux Software Raid Level 6

Post by lawern » Mon Feb 28, 2011 7:22 am

Alt wrote:Did you substitute the missing 2 disks with the Missing disk objects?
Yes, I had substituted the missing 2 disks with "Missing Disk".
But in this configuration most of the files have wrong content.

Now, after adding a fifth disk everything looks good.

Thanks

Lars

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