How to Remove Raid in Linux

Recently I have created software raid 5 in Linux and mounted on a directory to store data on it. Now I want to remove Raid md device.

In this article I will show how to remove raid md device in Linux. Follow this tutorial : How to configure raid?

Remove Raid in Linux

Follow the below steps to remove the raid md device in Linux.

1. Find the below details.

Operating system  : CentOS release 6.5 (Final)
RAID device 	  : /dev/md0
		  : md0 : active raid5 sdd1[4] sdc1[3] sdb1[1] sda1[0]

As you can see I have md0 device which contain four active Disks like below.

2. Check the Raid status.

# cat /proc/mdstat 
Personalities : [raid6] [raid5] [raid4] 
md0 : active raid5 sdd1[4] sdc1[3] sdb1[1] sda1[0]
      4189184 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      
unused devices: 

[root@srv6 ~]# mdadm --detail /dev/md0
/dev/md0:
        Version : 1.2
  Creation Time : Wed Apr 19 01:47:10 2017
     Raid Level : raid5
     Array Size : 4189184 (4.00 GiB 4.29 GB)
  Used Dev Size : 2094592 (2045.84 MiB 2144.86 MB)
   Raid Devices : 4
  Total Devices : 4
    Persistence : Superblock is persistent

    Update Time : Wed Apr 19 21:59:48 2017
          State : clean 
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : srv6:0  (local to host srv6)
           UUID : 4e7c1751:cd467d3f:8e86a6a1:3c88f6a4
         Events : 139

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1
       3       8       33        2      active sync   /dev/sdc1
       4       8       49        3      active sync   /dev/sdd1

3. Remove RAID 5 device. First of all we should take backup of data stored in RAID device in case it needed and unmount it from filesystem like below.

# df -hTP /raid5_disk/
Filesystem     Type  Size  Used Avail Use% Mounted on
/dev/md0       ext4  5.9G  213M  5.4G   4% /raid5_disk

# umount /raid5_disk

# sed -i '/md0/d' /etc/fstab

4. Now we can stop or deactivate RAID device by running below command from root user.

# mdadm --stop /dev/md0
mdadm: stopped /dev/md0

After stopping the raid device you, can remove md device.

# mdadm --remove /dev/md0

In some OS, i find we can’t remove md device because md device is already removed after stopped with stop option as above.

# mdadm  --stop /dev/md0 
mdadm: stopped /dev/md0

# cat /proc/mdstat 
Personalities : [raid6] [raid5] [raid4] 
unused devices: 

# ls -l /dev/md0
ls: cannot access /dev/md0: No such file or directory

# mdadm  --remove /dev/md0 
mdadm: error opening /dev/md0: No such file or directory

Raid device successfully removed. Now we can Finally remove superblocks from all associated disks, like below.

# mdadm --zero-superblock /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1

FAQs

Questions 1 : How can I remove RAID 1 without losing data?

Answer : You can removed RAID 1 mirror without any data loss. If the only volume on the array or the the first volume in a matrix RAID configuration.

Question 2 : What will happen if I delete the RAID volume?

Answer : If the computer booted with RAID 0 and if the raid volume is deleted then your compute became unbeatable.

Question 3 : How to disable RAID mode?

Answer : If you disable RAID function may be you loss your data. Make sure to create a backup before disabling RAID.