'''THIS SERVER IS DOWN AS NOW 2014-April'''



==software raid mdadm==
http://www.cyberciti.biz/faq/linux-creating-software-raid-one-arrays/

http://zackreed.me/articles/38-software-raid-5-in-debian-with-mdadm

===fdisk / gpartd / parted===
if the disk size > 2.2T, need to use parted to create partition
 parted /dev/sdb
 parted /dev/sdc
 parted /dev/sdd

===If the device contains a valid md superblock, the block is overwritten with zeros:===
 mdadm --zero-superblock /dev/sdb /dev/sdc /dev/sdd

===Create RAID1 using /dev/sdb1 and /dev/sdc1===
 mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1

or

===Create RAID5 using /dev/sdb1, /dev/sdc1 and /dev/sdd1===
 mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3 [--spare-devices=1] /dev/sd[bcd]1

===Format /dev/md0 as ext3:=== 
we would like to use ext4, but with xenserver, there is no ext4 option.
 mkfs.ext3 /dev/md0

===test Mount /dev/md0===
 mkdir /raid1  // for test RAID1
or
 mkdir /raid5  // for test RAID5

 mount /dev/md0 /raid1
 df -H

===set auto boot up===
we have set up the array, we need to edit the mdadm configuration file so that it knows how to assemble the array when the system reboots.
 echo "DEVICE partitions" > /etc/mdadm.conf
 echo "HOMEHOST fileserver" >> /etc/mdadm.conf
 echo "MAILADDR youruser@gmail.com" >> /etc/mdadm.conf
 mdadm --detail --scan

===add to xenserver===
 xe sr-create content-type=user type=ext device-config:device=/dev/md0 shared=false name-label="local raid5md0"

===RAID expansion===
 mdadm --manage /dev/md0 --add /dev/sde1  --> if new disk is named "/dev/sde"
 mdadm --grow /dev/md0 -n4                --> assuming an increase of only one disk