Did --zero-superblock by mistake ... How can I get back data ?

Hi,

On a RAID 5 array which is composed by 5 hdd, I did mdadm --zero-superblocks on each hdd because I thought it was required to use the array on a new system....

But now, I cannot mdadm --assemble the array. It says :

mdadm: no RAID superblock on /dev/sda
mdadm: /dev/sda has no superblock - assembly aborted

Is it possible to assemble this array because I don't want to lose my data... Someone told me that I can do a :

mdadm -Cv /dev/md0 -l5 -n5 /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/hdc

But if do that, all the data on the raid will be lost or not ?

Is there an other way to get back these data ?

Thank you very much for your help.

Quoted 13 lines · Raphael Delaporte

Hi,

On a RAID 5 array which is composed by 5 hdd, I did mdadm --zero-superblocks on each hdd because I thought it was required to use the array on a new system....

But now, I cannot mdadm --assemble the array. It says :

mdadm: no RAID superblock on /dev/sda
mdadm: /dev/sda has no superblock - assembly aborted

Is it possible to assemble this array because I don't want to lose my data... Someone told me that I can do a :

Quoted 8 lines

mdadm -Cv /dev/md0 -l5 -n5 /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/hdc

But if do that, all the data on the raid will be lost or not ?

Is there an other way to get back these data ?

Thank you very much for your help.

I would try to recreate the raid5 array with *1 missing disk,* then try to mount the array (read only) and verify the data.

For example,
mdadm -C /dev/md0 -l 5 -c 32 -p ls -n 5 /dev/sda /dev/sdb /dev/sdc /dev/sdd missing

Notes:
If you used /etc/mdadm.conf, specify the disk order on the ARRAY line with 1 missing disk to be safe.
I specified the mdadm default chunk size (32K) and default parity algorithm (left-symmetric). You may have to use other values. You should change the order of the disks if your data is invalid.

Signature · 7 lines

Regards,
Mike T.

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