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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 //Show the details of the md0 array mdadm -E /dev/sda1 //Examine the Hard Disk sda1 cat /proc/mdstat //Shows the RAID array. UU=2 disks are fine. _U=1 disk needsss rebuilding mdadm –examine –scan //Shows the disks and their array. This information should be in the config file /etc/mdadm/mdadm.conf

Monitoring a RAID Array

ps -eaf //It should show the Monitor already! - /sbin/mdadm -F -i /var/run/ -m root -f -s //To monitor manually → mdadm –monitor –mail=root –delay=300 /dev/md0 nohup mdadm –monitor –mail=sysadmin –delay=300 /dev/md0 & //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:

//For Disk 1 grub device (hd0) /dev/sda root (hd0,0) setup (hd0)

//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 //chose which ever one is necessary //MAKE SURE TO DO THE GRUB BOOT LOADER - OTHERWISE PC WONT BOOT!!!!!!!!!!!

Further Information can be found at: <br> <br> <br> //Excellent <br>

base_install_of_debian_sarge_with_raid.txt · Last modified: 2022/07/19 21:13 by