====== Base_Install_of_Debian_Sarge_with_RAID ======

====== RAID 1 and mdadm ======
**This is a "How to" setup for RAID 1 on Linux.** It is applied to Debian sarge, however through the use of mdadm (multiple devices admin) it should be able to work on various Linux installs.


===== RAID 1 setup with a NEW install of Debian Sarge =====
Two hard disks of 2gb in total each were setup with RAID. This is done through some careful looking in the Debian Install process.
  * Make sure also to Choose - **linux26** when booting the Debian Install CD
  * Follow the install procedure for Creating Partitions VERY carefully.
  * The key point is - when creating a volume, do not choose ext3 -> choose "RAID Volume" for Both hard disks. 
  * From the install process it is possible to get the RAID 1 array working perfectly. Note: LVM is NOT used.


===== General Information on Managing RAID =====
mdadm is the tool used to control and manage the RAID array.
 mdadm -D /dev/md0   <nowiki>//</nowiki>Show the details of the md0 array
 mdadm -E /dev/sda1 <nowiki>//</nowiki>Examine the Hard Disk sda1
 cat /proc/mdstat    <nowiki>//</nowiki>Shows the RAID array. [[UU]]=2 disks are fine. [[_U]]=1 disk needsss rebuilding
 mdadm --examine --scan <nowiki>//</nowiki>Shows the disks and their array. This information should be in the config file /etc/mdadm/mdadm.conf


===== Monitoring a RAID Array =====
 ps -eaf  <nowiki>//</nowiki>It should show the Monitor already! - /sbin/mdadm -F -i /var/run/mdadm.pid -m root -f -s
 <nowiki>//</nowiki>To monitor manually ->
 mdadm --monitor --mail=root --delay=300 /dev/md0
 nohup mdadm --monitor --mail=sysadmin --delay=300 /dev/md0 &  <nowiki>//</nowiki>The & will background the monitoring


===== Prepare BOTH Hard Disks so EITHER one will boot via Grub =====
This MUST also be DONE after REBUILDING an ARRAY!!! <br>
The MBR has to be reinstalled after having replaced the broken disk: 

 <nowiki>//</nowiki>For Disk 1
 grub 
 device (hd0) /dev/sda 
 root (hd0,0) 
 setup (hd0) 
 
 <nowiki>//</nowiki>For Disk 2
 grub 
 device (hd1) /dev/sdb 
 root (hd1,0) 
 setup (hd1) 

===== How to Rebuild an Array: =====
 mdadm --add /dev/md0 /dev/sda1
 mdadm --add /dev/md0 /dev/sdb1
 <nowiki>//</nowiki>chose which ever one is necessary
 <nowiki>//</nowiki>**MAKE SURE TO DO THE GRUB BOOT LOADER - OTHERWISE PC WONT BOOT!!!!!!!!!!!**

----
Further Information can be found at: <br>
http://www.networknewz.com/2003/0113.html <br>
http://www.linuxmanpages.com/man8/mdadm.8.php <br>
http://www.planamente.ch/emidio/pages/linux_howto_root_lvm_raid.php#Creating%20RAID%20devices  <nowiki>//</nowiki>Excellent <br>