How to Setup Linux RAID 1 Device on RHEL

Now you can begin to set up the RAID 1 array with the two partitions in hand. You can use the mdadm command to create any RAID array.

Syntax: mdadm [options] 
Options: -a, xx Adds a disk into a current array 
-C, —create Creates a new RAID array 
-D, —detail Prints the details of an array 
-G, —grow Changes the size or shape of an active array
-f, xx Fails a disk in the array
-l, —level Specifies level (type) of RAID array to create 
-n, —raid-devices Specifies the devices in the RAID array 
-q, —quiet Species not to show output 
-S, —stop Stops an array 
-v, —verbose Provides verbose output

Now Let’s create Linux RAID 1 device.

[root@rhel1 ~]# mdadm -Cv /dev/md0 --level=1 -n2 /dev/sdc1 /dev/sdd1
mdadm: Note: this array has metadata at the start and
may not be suitable as a boot device. If you plan to
store '/boot' on this device please ensure that
your boot-loader understands md/v1.x metadata, or use
--metadata=0.90
mdadm: size set to 1044181K
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.
[root@rhel1 ~]#

View the status of newly created Linux RAID 1 using below command.

[root@rhel1 ~]# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sdd1[1] sdc1[0]
1044181 blocks super 1.2 [2/2] [UU]

unused devices: <none>
[root@rhel1 ~]# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sdd1[1] sdc1[0]
1044181 blocks super 1.2 [2/2] [UU]

unused devices: <none>