How to Configure and Test RAID 5 on Linux Mint 20

Now list the disk of the RAID is mounted or not

root@linuxhelp:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            1.9G     0  1.9G   0% /dev
tmpfs           391M  1.6M  390M   1% /run
/dev/sda6        16G  6.8G  7.5G  48% /
tmpfs           2.0G     0  2.0G   0% /dev/shm
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           2.0G     0  2.0G   0% /sys/fs/cgroup
/dev/sda1       3.7G   15M  3.4G   1% /swap
/dev/sda5       945M  108M  773M  13% /boot
tmpfs           391M   16K  391M   1% /run/user/1000
/dev/md0        2.0G  6.0M  1.9G   1% /data

Now I am get into the newly created directory

root@linuxhelp:~# cd /data/

Inside the directory I will create some files on it

root@linuxhelp:/data# touch linuxhelp.txt

Now I am going to edit the text file by using vim command

root@linuxhelp:/data# vim linuxhelp.txt 
Welcome to LinuxHelp

Now I am list the directory

root@linuxhelp:/data# ls -la
total 28
drwxr-xr-x  3 root root  4096 Jan 20 14:18 .
drwxr-xr-x 25 root root  4096 Jan 20 14:14 ..
-rw-r--r--  1 root root    21 Jan 20 14:18 linuxhelp.txt
drwx------  2 root root 16384 Jan 20 14:13 lost+found

Now I am going to test RAID 5 for that first I am fail the one partition from the RAID

root@linuxhelp:/data# mdadm /dev/md0 -f /dev/sdb1
mdadm: set /dev/sdb1 faulty in /dev/md0

Now I will view the RAID details if the partition is failed or not

root@linuxhelp:/data# mdadm --detail /dev/md0 
/dev/md0:
           Version : 1.2
     Creation Time : Wed Jan 20 14:12:23 2021
        Raid Level : raid5
        Array Size : 2093056 (2044.00 MiB 2143.29 MB)
     Used Dev Size : 1046528 (1022.00 MiB 1071.64 MB)
      Raid Devices : 3
     Total Devices : 3
       Persistence : Superblock is persistent
       Update Time : Wed Jan 20 14:21:03 2021
             State : clean, degraded 
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 1
     Spare Devices : 0
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
              Name : linuxhelp:0  (local to host linuxhelp)
              UUID : 01efc0c7:2c10bf97:ba096e3f:40d25615
            Events : 20
    Number   Major   Minor   RaidDevice State
       -       0        0        0      removed
       1       8       33        1      active sync   /dev/sdc1
       3       8       49        2      active sync   /dev/sdd1

       0       8       17        -      faulty   /dev/sdb1

After that I will check the directory if the data are corrupted or not

root@linuxhelp:/data# ls -la
total 28
drwxr-xr-x  3 root root  4096 Jan 20 14:18 .
drwxr-xr-x 25 root root  4096 Jan 20 14:14 ..
-rw-r--r--  1 root root    21 Jan 20 14:18 linuxhelp.txt
drwx------  2 root root 16384 Jan 20 14:13 lost+found

Now I will remove the failed drive from the RAID

root@linuxhelp:/data# mdadm /dev/md0 -r /dev/sdb1
mdadm: hot removed /dev/sdb1 from /dev/md0

Now I am create SDE partition and add the partition to the RAID

root@linuxhelp:/data# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE  MOUNTPOINT
sda       8:0    0   20G  0 disk  
├─sda1    8:1    0  3.7G  0 part  /swap
├─sda2    8:2    0    1K  0 part  
├─sda5    8:5    0  976M  0 part  /boot
└─sda6    8:6    0 15.3G  0 part  /
sdb       8:16   0   20G  0 disk  
└─sdb1    8:17   0    1G  0 part  
sdc       8:32   0   20G  0 disk  
└─sdc1    8:33   0    1G  0 part  
  └─md0   9:0    0    2G  0 raid5 /data
sdd       8:48   0    2G  0 disk  
└─sdd1    8:49   0    1G  0 part  
  └─md0   9:0    0    2G  0 raid5 /data
sde       8:64   0    2G  0 disk  
sr0      11:0    1  1.9G  0 rom   

root@linuxhelp:/data# fdisk /dev/sde
Welcome to fdisk (util-linux 2.34).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0x5a68dcc7.
Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 
First sector (2048-4194303, default 2048): 
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-4194303, default 4194303): +1G
Created a new partition 1 of type 'Linux' and of size 1 GiB.
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): fd
Changed type of partition 'Linux' to 'Linux raid autodetect'.
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

List the disk by executing the following command

root@linuxhelp:/data# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE  MOUNTPOINT
sda       8:0    0   20G  0 disk  
├─sda1    8:1    0  3.7G  0 part  /swap
├─sda2    8:2    0    1K  0 part  
├─sda5    8:5    0  976M  0 part  /boot
└─sda6    8:6    0 15.3G  0 part  /
sdb       8:16   0   20G  0 disk  
└─sdb1    8:17   0    1G  0 part  
sdc       8:32   0   20G  0 disk  
└─sdc1    8:33   0    1G  0 part  
  └─md0   9:0    0    2G  0 raid5 /data
sdd       8:48   0    2G  0 disk  
└─sdd1    8:49   0    1G  0 part  
  └─md0   9:0    0    2G  0 raid5 /data
sde       8:64   0    2G  0 disk  
└─sde1    8:65   0    1G  0 part  
sr0      11:0    1  1.9G  0 rom   

Now format the sde1 drive to ext4 file system by using the following command

root@linuxhelp:/data# mkfs.ext4 /dev/sde1 
mke2fs 1.45.5 (07-Jan-2020)
Creating filesystem with 262144 4k blocks and 65536 inodes
Filesystem UUID: a25bc884-ccef-47e6-8056-a2cafde432a4
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376
Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

After the format is completed then I am add the sde1 drive to the RAID

root@linuxhelp:/data# mdadm /dev/md0 --add /dev/sde1 
mdadm: added /dev/sde1

Now I am list the RAID for if the sde1 is added or not

root@linuxhelp:/data# mdadm --detail /dev/md0 
/dev/md0:
           Version : 1.2
     Creation Time : Wed Jan 20 14:12:23 2021
        Raid Level : raid5
        Array Size : 2093056 (2044.00 MiB 2143.29 MB)
     Used Dev Size : 1046528 (1022.00 MiB 1071.64 MB)
      Raid Devices : 3
     Total Devices : 3
       Persistence : Superblock is persistent
       Update Time : Wed Jan 20 14:28:43 2021
             State : clean 
    Active Devices : 3
   Working Devices : 3
    Failed Devices : 0
     Spare Devices : 0
            Layout : left-symmetric
        Chunk Size : 512K
Consistency Policy : resync
              Name : linuxhelp:0  (local to host linuxhelp)
              UUID : 01efc0c7:2c10bf97:ba096e3f:40d25615
            Events : 40
    Number   Major   Minor   RaidDevice State
       4       8       65        0      active sync   /dev/sde1
       1       8       33        1      active sync   /dev/sdc1
       3       8       49        2      active sync   /dev/sdd1

Finally list the directory if the files are stored are not

root@linuxhelp:/data# ls -la
total 28
drwxr-xr-x  3 root root  4096 Jan 20 14:18 .
drwxr-xr-x 25 root root  4096 Jan 20 14:14 ..
-rw-r--r--  1 root root    21 Jan 20 14:18 linuxhelp.txt
drwx------  2 root root 16384 Jan 20 14:13 lost+found

With this method, the Configuration and Test RAID 5 on Linux Mint 20 comes to an end.