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 -l /dev/sda

or

sgdisk -p /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

Verify sfdisk recognizes your source partitions. If not, try sgdisk.

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

Be careful not to write to the wrong disk or you will have a very bad day!

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

sfdisk -d /dev/sda | sfdisk /dev/sdb

or

sgdisk /dev/sda -R /dev/sdb
sgdisk -G /dev/sdb

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)