====== RAID ======

**raid howto is located in [[linux:filesystems:crypto_raid|]]**


===== RAID recovery =====

https://raid.wiki.kernel.org/index.php/RAID_Recovery


if a raid is degraded, save superblock infos first:

  mdadm --examine /dev/sd[abcd]1 > /etc/_raid/mdadm--examine_2013-03-10


check, whats up:
  mdadm --detail /dev/md1

re-add a removed device:
  mdadm  /dev/md1 --add /dev/sda2

watch revovery:
  watch cat /proc/mdstat 


update existing initramfs:
  update-initramfs -u -k all 

===== RAID setup changes =====

update the raid config - achtung ">>" adds to the files, ">" overwrites:
  mdadm --examine --scan >> /etc/mdadm/mdadm.conf 


you need to update initramfs: to find the root raid

make sure these modules are included in /etc/initramfs-tools/modules
  raid0
  raid1
  md

re-create inramfs:
  update-initramfs -u -k all

check in /boot, if they got recreated!


  dpkg-reconfigure mdadm 
  
===== RAID Monitoring Tools / resync =====

Check RAID Status: 

   watch -n1 cat /proc/mdstat
   
   mdadm --detail /dev/md2


Check Resync Speed Limits:
  sysctl dev.raid.speed_limit_min
  sysctl dev.raid.speed_limit_max

Reconfigure Speed Limits:
  sysctl -w dev.raid.speed_limit_min=50000   # increase speed -> higher system load 
  sysctl -w dev.raid.speed_limit_max=5000    # lower speed -> less load, more time


Links:
  * https://www.cyberciti.biz/tips/linux-raid-increase-resync-rebuild-speed.html
  *