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I've been searching for hours and giving up / too scared to delete all my data. I have a file server running CentOS 6.5 which has 4 WD RED 2TB drives (all > 1 year old) in software raid 5 with mdadm, and some other drives (not important). I used LVM on top of the RAID5 for easy management and partitioned the volume group as ext4.

All of this worked really well until I needed to reboot. Apparently I forgot to save the mdadm settings to /etc/mdadm.conf and because of this the RAID failed. It contained some info but I've accidentally deleted its contents by running some command I've found via Google.

After hours of searching I tried to run mdadm -assemble, but this tells me no drive has an super block:

# mdadm --assemble /dev/md0 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 
mdadm: no recogniseable superblock on /dev/sdb1
mdadm: /dev/sdb1 has no superblock - assembly aborted

Also tried without the partition numbers (/dev/sdb) but get the same result. Then I came across this command:

# mdadm --assemble --scan --verbose
mdadm: looking for devices for further assembly
mdadm: no recogniseable superblock on /dev/dm-3
mdadm: no recogniseable superblock on /dev/dm-2
mdadm: no recogniseable superblock on /dev/dm-1
mdadm: no recogniseable superblock on /dev/dm-0
mdadm: no recogniseable superblock on /dev/sdg1
mdadm: Cannot assemble mbr metadata on /dev/sdg
mdadm: no recogniseable superblock on /dev/sda1
mdadm: Cannot assemble mbr metadata on /dev/sda
mdadm: no recogniseable superblock on /dev/sdf1
mdadm: Cannot assemble mbr metadata on /dev/sdf
mdadm: no recogniseable superblock on /dev/sdh1
mdadm: Cannot assemble mbr metadata on /dev/sdh
mdadm: Cannot assemble mbr metadata on /dev/sdc1
mdadm: Cannot assemble mbr metadata on /dev/sdc
mdadm: Cannot assemble mbr metadata on /dev/sdd1
mdadm: Cannot assemble mbr metadata on /dev/sdd
mdadm: no recogniseable superblock on /dev/sde1
mdadm: Cannot assemble mbr metadata on /dev/sde
mdadm: no recogniseable superblock on /dev/sdb1
mdadm: Cannot assemble mbr metadata on /dev/sdb
mdadm: no recogniseable superblock on /dev/sdk1
mdadm: Cannot assemble mbr metadata on /dev/sdk
mdadm: Cannot assemble mbr metadata on /dev/sdj2
mdadm: Cannot assemble mbr metadata on /dev/sdj1
mdadm: Cannot assemble mbr metadata on /dev/sdj
mdadm: no recogniseable superblock on /dev/sdi2
mdadm: no recogniseable superblock on /dev/sdi1
mdadm: Cannot assemble mbr metadata on /dev/sdi
mdadm: No arrays found in config file or automatically

The strange thing is if I run specific on the drives it gives me the info:

# mdadm --examine /dev/sdc1
/dev/sdc1:
   MBR Magic : aa55
Partition[0] :    432871117 sectors at   3224498923 (type 07)
Partition[1] :   1953460034 sectors at   3272020941 (type 16)
Partition[3] :    924335794 sectors at     50200576 (type 00)

Same result on sdd1, but not on sdb1 and on sde1, ie. the other 2 drives.

At this point I've given up and don't want to break the RAID. It contains very important data which has no backups (I know really stupid, but I was working on a backup system).

Does anyone know how to fix this or recommendation on what to do next? It is really important that I keep the data or can backup the data which is stored on the array.

UPDATE Since i was to scared to touch it myself and risking completely losing the data. I hired someone from freelancer.com. I got the data back now and making backups of it. After this i will completely rebuild the array to prevent this from happening again. I will also ask him for the recovery process en post it here so other people with the same problem can try to recover there array.

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    Is your /etc/mdadm.conf not intact then? I'd start with recreating that from the RAID and rebooting: mdadm --detail --scan >> /etc/mdadm.conf, but be sure not to destroy a pre-existing mdadm.conf file. If there's one, you can move it out of the way first: mv /etc/mdadm.conf /etc/mdadm.conf_PREV. – slm Jul 5 '14 at 21:46
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    A missing mdadm.conf is never a problem. You seem to suffer from missing metadata (no arrays found). You seem to be having partition tables on partitions, that's all the --examine output is showing. Check if there is any metadata to be found on them (going via one of losetup --partscan, partx, kpartx if you must). Make sure to do all of this in read only mode. – frostschutz Jul 5 '14 at 23:58

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