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I have (had) a large RAID5 array (3x8TB) up and running on Ubuntu 16.04 using the guide on the following page:

https://www.digitalocean.com/community/tutorials/how-to-create-raid-arrays-with-mdadm-on-ubuntu-16-04

The array seemed to be running well, and was automatically loaded on re-boot etc, all good!

Today however, i was formatting some USB drives in gparted and it popped up some error about the partition table for the raid drives appearing corrupted, and using the backup. I didn't think much of this at the time, but it looks like that deleted the partition tables, and now i have no array.

Interestingly a raid 0 array i created at the same time is fine.

Does anyone know a safe(ish) way of recovering or recreating the partition tables, and re-loading the array?

Happy to provide any other outputs that are helpful

lsblk shows all of the disks are there and detected. sda,b,c are the raid0 array which is fine. sdd,e,f should have partitions and be part of a raid5 array (md1).


$ lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT
NAME          SIZE FSTYPE            TYPE  MOUNTPOINT
sda         232.9G                   disk  
└─sda1      232.9G linux_raid_member part  
  └─md0     698.3G ext4              raid0 /fast
sdb         232.9G                   disk  
└─sdb1      232.9G linux_raid_member part  
  └─md0     698.3G ext4              raid0 /fast
sdc         232.9G                   disk  
└─sdc1      232.9G linux_raid_member part  
  └─md0     698.3G ext4              raid0 /fast
sdd           7.3T                   disk  
sde           7.3T                   disk  
sdf           7.3T                   disk  
nvme0n1     238.5G                   disk  
├─nvme0n1p1 119.2G ext4              part  /
└─nvme0n1p5 119.3G swap              part  [SWAP]

Only 1 raid array is found by mdstat


$ cat /proc/mdstat 
Personalities : [raid0] [linear] [multipath] [raid1] [raid6] [raid5] [raid4] [raid10] 
md0 : active raid0 sdc1[2] sdb1[1] sda1[0]
      732198912 blocks super 1.2 64k chunks

unused devices: 

$ cat /etc/mdadm/mdadm.conf 
\# mdadm.conf
CREATE owner=root group=disk mode=0660 auto=yes
HOMEHOST 
MAILADDR root
ARRAY /dev/md/0 metadata=1.2 name=Octavius:0 UUID=b893dcb8:24d049e3:c810f89f:00c5f1b7
ARRAY /dev/md1 metadata=1.2 name=Octavius:1 UUID=5858458f:6ebb00c9:c30c4aa6:5737eedb
0

GParted most probably warned you about an error in GPT. As you claim:

I didn't think much of this at the time

That was kind of the cause of the problem, as you - I presume - clicked "Yes, fix" or similarly.

I think you destroyed the partition table by doing so.

To answer your question:

Does anyone know a safe(ish) way of recovering or recreating the partition tables, and re-loading the array?

I don't think there is any, I am sorry.

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