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06-06-2012, 03:39 AM
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#1
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LQ Newbie
Registered: Jun 2012
Posts: 3
Rep: 
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Recovering data from a busted RAID5 array
Hi all,
I have been using a 4-disk RAID5 array using an Acer EasyStore NAS.
As was inevitable - the device has failed and no longer recognizes the Array.
I am Now attempting to back up the data from these drives.
So far I have:
Connected 3x of the 4 drives to SATA ports 0-3 on my motherboard.
Booted a Knoppix LiveCD (latest version at time of this writing)
Been able to see the drives in the file explorer as sda4, sdb4, sdc4
Google tells me I need to somehow restore the array using the MDADM command. But I have not been able to figure out the exact commands.
Can anyone help? I am a complete newbie when it comes to Linux.
Thanks
Brett
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06-06-2012, 04:46 AM
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#2
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Senior Member
Registered: Jan 2010
Location: SI : 45.9531, 15.4894
Distribution: CentOS, OpenNA/Trustix, testing desktop openSuse 12.1 /Cinnamon/KDE4.8
Posts: 1,144
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Hi,
I don't know exactly, but take a look here if it will help you out.
good luck
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06-06-2012, 04:51 AM
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#3
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LQ Newbie
Registered: Jun 2012
Posts: 3
Original Poster
Rep: 
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Quote:
Originally Posted by lithos
Hi,
I don't know exactly, but take a look here if it will help you out.
good luck
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Thanks for that. Unfortunately that article covers RAID1 which seems to be far simpler than RAID5.
For some more information, see the results of fdisk -l:
Code:
root@Microknoppix:/home/knoppix# fdisk -l
Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sda1 1 66 530113+ 82 Linux swap / Solaris
/dev/sda2 198 121471 974133405 83 Linux
/dev/sda4 67 197 1052257+ 83 Linux
Partition table entries are not in disk order
Disk /dev/sdc: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdc1 1 66 530113+ 82 Linux swap / Solaris
/dev/sdc2 198 121471 974133405 83 Linux
/dev/sdc4 67 197 1052257+ 83 Linux
Partition table entries are not in disk order
Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdb1 1 66 530113+ 82 Linux swap / Solaris
/dev/sdb2 198 121471 974133405 83 Linux
/dev/sdb4 67 197 1052257+ 83 Linux
Partition table entries are not in disk order
Disk /dev/sdd: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdd1 1 66 530113+ 82 Linux swap / Solaris
/dev/sdd2 198 121471 974133405 83 Linux
/dev/sdd4 67 197 1052257+ 83 Linux
Partition table entries are not in disk order
Here is the command I am currently attempting:
Code:
root@Microknoppix:/home/knoppix# mdadm --assemble /dev/md0 /dev/sd[abcd]2
mdadm: /dev/md0 assembled from 3 drives - not enough to start the array while not clean - consider --force.
I'm not sure if it's right, therefore i am reluctant to re-run with --force.
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06-06-2012, 10:01 AM
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#4
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Senior Member
Registered: Jan 2010
Location: SI : 45.9531, 15.4894
Distribution: CentOS, OpenNA/Trustix, testing desktop openSuse 12.1 /Cinnamon/KDE4.8
Posts: 1,144
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Recreate soft-raid array in linux
Can you try it like this auto detect devices?
There is really not much about recovering soft-raid on linux on internet and I don't have any idea whatsoever with it, sorry.
Can anyone here at LQ please help out.
wish you good luck
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06-06-2012, 01:55 PM
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#5
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LQ Guru
Registered: Nov 2010
Location: Colorado
Distribution: OpenSUSE, CentOS
Posts: 5,573
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When you say the "device" has failed, are you referring to the Acer NAS?
You may be able to RMA the NAS, and just put the drives in. It depends on how the NAS stores the array information...on most hardware RAID cards the array information is stored on the disks themselves, so you can swap out the controller and the array stays in-tact. Software RAIDs are a bit harder to recover in the event of a failure...unfortunately I don't have any experience with that (most of my systems are hardware RAID).
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06-08-2012, 03:31 AM
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#6
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LQ Newbie
Registered: Jun 2012
Posts: 3
Original Poster
Rep: 
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Got it working!
Was just a matter of running the command from earlier with --force.
Backing up to USB drive now.
Thanks for the help!
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06-08-2012, 05:12 AM
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#7
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Senior Member
Registered: Jan 2010
Location: SI : 45.9531, 15.4894
Distribution: CentOS, OpenNA/Trustix, testing desktop openSuse 12.1 /Cinnamon/KDE4.8
Posts: 1,144
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Great,
thanks for reporting back for future references that others may find this.
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