6.3.2. Creating a New RAID Device

To create a new RAID device, use the command in the following form as root:
mdadm --create raid_device --level=level --raid-devices=number component_device
This is the simplest way to create a RAID array. There are many more options that allow you to specify the number of spare devices, the block size of a stripe array, if the array has a write-intent bitmap, and much more. All these options can have a significant impact on the performance, but are beyond the scope of this document. For more detailed information, refer to the CREATE MODE section of the mdadm(8) manual page.

Example 6.2. Creating a new RAID device

Assume that the system has two unused SCSI disk drives available, and that each of these devices has exactly one partition of the same size:
~]# ls /dev/sd*
/dev/sda  /dev/sda1  /dev/sdb  /dev/sdb1
To create /dev/md3 as a new RAID level 1 array from /dev/sda1 and /dev/sdb1, run the following command:
~]# mdadm --create /dev/md3 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1
mdadm: array /dev/md3 started.