Step by Step: CentOS – RAID 0

Get a list of available hard drive


ls -lh /dev/sd* or ls -lh /dev/hd*

Example Output:

[root@sKy-Centos ~]# ls -lh /dev/sd*
brw-rw----. 1 root disk 8, 0 Jun 13 22:53 /dev/sda
brw-rw----. 1 root disk 8, 1 Jun 13 22:53 /dev/sda1
brw-rw----. 1 root disk 8, 2 Jun 13 22:53 /dev/sda2
brw-rw----. 1 root disk 8, 16 Jun 13 22:53 /dev/sdb
brw-rw----. 1 root disk 8, 17 Jun 13 22:55 /dev/sdb1
brw-rw----. 1 root disk 8, 32 Jun 13 22:53 /dev/sdc
brw-rw----. 1 root disk 8, 33 Jun 13 22:55 /dev/sdc1
[root@sKy-Centos ~]#

Suppose we want to create RAID 0 from /dev/sdb and /dev/sdc and delete all partition inside (fresh RAID installation).


fdisk /dev/sdb

On fdisk interface, use “p” to print partition table to screen, “d” to delete partition, “n” to create new partition, and “w” to write changes to disk. Do the same thing to /dev/sdc
Next, we need to create RAID partition, in this example, we use /dev/md0 as a new name for RAID partition

mdadm -C /dev/md0 --level=raid0 --raid-devices=2 /dev/sdb1 /dev/sdc1

If the system complaints about cannot continue because device is busy, try to reboot and run the command again or check if RAID is already running with this command

cat /proc/mdstat

Example Output:

[root@sKy-Centos ~]# cat /proc/mdstat
Personalities : [raid0]
md0 : active raid0 sdc1[1] sdb1[0]
10471424 blocks super 1.2 512k chunks

unused devices:

and stop it with

mdadm --stop /dev/md0

Create mount point for our new RAID 0 Partition, for example, we will use /widi as mount point.

mkdir /widi

Edit /etc/fstab and add that partition

/dev/md0 /widi /ext3 defaults 1 1

Format /dev/md0 before actual mounting

mkfs.ext3 /dev/md0

Finally, mount /widi

mount /widi

Some notes on mdadm. It is not necessary to had the same size for the RAID 0. mdadm will adjust so extra space on larger drive won’t be used for stripping.

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