RAID array is gone, please help

[raid@mueller.org]

I am hoping someone here will help me. Was reading this site...

https://raid.wiki.kernel.org/index.php/Linux_Raid

and it said to email this list if you've tried everything other than 
mdadm --create.


I am running Ubuntu 16.04. Machine name is fred. I used webmin to create 
a 4 disk RAID10 array yesterday. I moved all my data onto the array.

Today, I had to reboot my PC. The resync was still not done, but I read 
online that it's OK to boot during resync. After boot, my array was 
gone. I checked syslog, and it just has this line:

DeviceDisappeared event detected on md device /dev/md0

I did not partition my disks before building the array. So I believe the 
array consisted of /dev/sdc, /dev/sdd, /dev/sde, and /dev/sdf.

Here's some info...

stephen@fred> lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 117.4G  0 disk
├─sda1   8:1    0 109.7G  0 part /
├─sda2   8:2    0     1K  0 part
└─sda5   8:5    0   7.7G  0 part [SWAP]
sdb      8:16   0 465.8G  0 disk
└─sdb1   8:17   0 465.8G  0 part
sdc      8:32   0   3.7T  0 disk
sdd      8:48   0   3.7T  0 disk
sde      8:64   0   3.7T  0 disk
sdf      8:80   0   3.7T  0 disk

stephen@fred> sudo mdadm --examine /dev/sdc
[sudo] password for stephen:
/dev/sdc:
    MBR Magic : aa55
Partition[0] :   4294967295 sectors at            1 (type ee)
stephen@fred>
stephen@fred> sudo mdadm --examine /dev/sdc1
mdadm: cannot open /dev/sdc1: No such file or directory
stephen@fred>
stephen@fred> sudo mdadm --examine /dev/sdd
/dev/sdd:
    MBR Magic : aa55
Partition[0] :   4294967295 sectors at            1 (type ee)
stephen@fred>
stephen@fred> sudo mdadm --examine /dev/sde
/dev/sde:
    MBR Magic : aa55
Partition[0] :   4294967295 sectors at            1 (type ee)
stephen@fred>
stephen@fred> sudo mdadm --examine /dev/sdf
/dev/sdf:
    MBR Magic : aa55
Partition[0] :   4294967295 sectors at            1 (type ee)

stephen@fred> sudo mdadm --assemble --force /dev/md0 /dev/sdc /dev/sdd 
/dev/sde /dev/sdf
mdadm: Cannot assemble mbr metadata on /dev/sdc
mdadm: /dev/sdc has no superblock - assembly aborted

Thank you for any help you can provide.