http://wiki.centos.org/HowTos/SoftwareRAIDonCentOS5

http://wiki.xtronics.com/index.php/Raid

http://robbat2.livejournal.com/231207.html

https://raid.wiki.kernel.org/index.php/Linux_Raid

http://archive.networknewz.com/2003/0113.html

Works on block devices, usually partitions. This is not like strictly-drive-oriented hardware RAID controllers.

mdadm --detail --scan --verbose

fdisk /dev/sda

Copy Patition Scheme: https://askubuntu.com/questions/57908/how-can-i-quickly-copy-a-gpt-partition-scheme-from-one-hard-drive-to-another/333923

Using fdisk, create matching partitions on various drives (block devices) of type fd Linux raid autodetect that will be assembled into arrays.

sfdisk -l /dev/sda

Disk /dev/sda: 8942 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

Device      Boot  Start     End    #cyls    #blocks  Id  System
/dev/sda1   *         0+    242     243-   1951866   fd  Linux raid autodetect
/dev/sda2           243     485     243    1951897+  fd  Linux raid autodetect
/dev/sda3           486     607     122     979965   82  Linux swap

Once you partition the first drive, use sfdisk to duplicate partitions from that first drive to other drives:

sfdisk -d /dev/sda | sfdisk /dev/sd[bcd]

http://robbat2.livejournal.com/231207.html

http://en.wikipedia.org/wiki/Mdadm

mdadm --create <[[array]]_device> -c <chunk_size> -l <raid_level> -n <active_disks> -x <spare_disks> <block_devices>

Here is a four-drive (partition) RAID5 example where one drive (partition) is a hot spare. Hot spare drives can serve multiple arrays (spare-group).

mdadm --create /dev/md0 --level=5 --raid-devices=3 --spare-devices=1 --spare-group=groupname /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1

http://www.kernelhardware.org/linux-add-share-hot-spare-device-software-raid/

mdadm --detail --scan --verbose

mdadm --add /dev/md0 /dev/sdb1
mdadm --add /dev/md1 /dev/sdb2
mdadm --add /dev/md2 /dev/sdb3

Not sure how beneficial or necessary this step is…

mdadm --detail --scan > /etc/mdadm/mdadm.conf

or for Centos:

mdadm --detail --scan --verbose > /etc/mdadm.conf

http://www.cyberciti.biz/faq/howto-copy-mbr/

Assuming you have identical disks with identical partitioning, use this command to copy the entire master boot record (boot code plus partition table) like this, adjusting for your needs:

dd if=/dev/sda of=/dev/sdb bs=512 count=1

http://wiki.centos.org/HowTos/GrubInstallation

grub

If you have a separate /boot partition:

grub> find /grub/stage1

If you don't:

grub> find /boot/grub/stage1

Then, based on the output of the find command:

grub> root (hd0,0)
grub> setup (hd2)