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.

Show Existing RAID

mdadm –detail –scan

Partitioning

fdisk /dev/sda 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]

Create Arrays

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 RAID5 example where one drive 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/

Add a Drive

mdadm –detail –scan

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

Create Conf FIle

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

or (Centos)

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

Last changed (in Tomboy): 2011-05-02 Note created (in Tomboy): 2010-12-18