Bdtyktl

I used mdadm to create a RAID 1 array using two 3TB drives. After the process, which took all night, I found that the two 3TB drives, /sdb and /sdc, have disappeared from the file explorer. Rebooted the system and they reappeared,then disappeared again after another reboot,they seem to be corrupted with error found in GParted where they can be found:

Corrupt extent header while reading journal super block</i>



<i>Unable to read the contents of this file system!

Because of this, some operations may be unavailable.

The cause might be a missing software package.

The following list of software packages is required for ext4 file system support:  e2fsprogs v1.41

I called the new RAID array md0, which now has a folder in /mnt/md0, which is empty.

There is a conf file in /etc/mdadm which reads:

# mdadm.conf

#

# !NB! Run update-initramfs -u after updating this file.

# !NB! This will ensure that initramfs has an uptodate copy.

#

# Please refer to mdadm.conf(5) for information about this file.

#



# by default (built-in), scan all partitions (/proc/partitions) and all

# containers for MD superblocks. alternatively, specify devices to scan, using

# wildcards if desired.

#DEVICE partitions containers



# automatically tag new arrays as belonging to the local system

HOMEHOST <system>



# instruct the monitoring daemon where to send mail alerts

MAILADDR root



# definitions of existing MD arrays



# This configuration was auto-generated on Mon, 24 Dec 2018 02:28:48 -0500 by mkconf

ARRAY /dev/md0 metadata=1.2 name=dna-computer:0 UUID=df25e6e6:cccb8138:aa9f4538:31608c33

Not sure if this helps but the command cat /proc/mdstat reads:

Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 

unused devices: <none>

This is whats mdadm does: it replaces your disks with a RAID identity, which is represented as /dev/md (md stands for multiple device). From that point, you don’t want direct access to your individual harddisks, because that would compromise the disk array.

As stated in the manual page of mdadm:

RAID devices are virtual devices created from two or more real block
devices. This allows multiple devices (typically disk drives or
partitions thereof) to be combined into a single device to hold (for
example) a single filesystem.

Also see for example this tutorial.