Here is an excerpt:
Creating an Array
mdadm --create) mode is used to create a new array. In this example I use
mdadm to create a RAID-0 at /dev/md0 made up of /dev/sdb1 and /dev/sdc1:
# mdadm --create --verbose /dev/md0 --level=0
--raid-devices=2 /dev/sdb1 /dev/sdc1
mdadm: chunk size defaults to 64K
mdadm: array /dev/md0 started.
--level option specifies which type of RAID to create in the same way that raidtools uses the
raid-level configuration line. Valid choices are 0,1,4 and 5 for RAID-0, RAID-1, RAID-4, RAID-5 respectively. Linear (
--level=linear) is also a valid choice for linear mode. The
--raid-devices option works the same as the
nr-raid-disks option when using /etc/raidtab and
mdadm commands take the format:
mdadm's options also has a short form that is less descriptive but shorter to type. For example, the following command uses the short form of each option but is identical to the example I showed above.
# mdadm -Cv /dev/md0 -l0 -n2 -c128 /dev/sdb1 /dev/sdc1