DokuWiki » Infrastructure » Operating System » CentOS 7

h1. Howto mdadm

have a look at: https://wiki.kobol.io/mdadm/

and also at: http://davidlu1001.github.io/2014/04/14/Linux-quick-guide-for-software-RAID/

or 

<pre><code class="bash">

## var

md=/dev/md0

pd1=/dev/hdc1   ## phys-Disk (Partition)

pd2=/dev/hda3   ## phys-Disk

mnt=/mnt/tmp    ## mount-dir test

mdconf=/etc/mdadm/mdadm.conf

fstab=/etc/fstab

backupdir=/mnt/space ## f. backup $pd1

## check variables

ls -l $md $pd1 $pd2

## pd sollten annaehernd gleiche Groesse haben.

## wichtig:  pd1 <= pd2

fdisk -l | egrep "$pd1|$pd2"

df -k $backupdir

## backup

dd if=$pd1 | gzip -c > $backupdir/$pd1.dd.gz-`date +%y%m%d`

## create RAID1

mdadm --create $md --level=1 --raid-devices=2 $pd1 missing

cat /proc/mdstat

## add 2. pd

mdadm $md -a $pd2

## create/restore fs (optional)

# gunzip -c $backupdir/$pd1.dd.gz-`date +%y%m%d` | dd of=$md

# mkfs.ext3 $md

## check

cat /proc/mdstat

mdadm --detail --scan

mount -r $md $mnt

ls -l $mnt/

umount $mnt

dd if=$pd1 bs=1k count=2 | hexdump -C

dd if=$pd2 bs=1k count=2 | hexdump -C

## change konfig

ls -la $mdconf

cp -p $mdconf $mdconf.old

[ `grep DEVICE $mdconf | wc -l` -eq 0 ] && echo 'DEVICE /dev/hd*[0-9] /dev/sd*[0-9]' > $mdconf

#mdadm --detail --scan >> $mdconf

echo "ARRAY $md level=raid1 num-devices=2 devices=$pd1,$pd2" >> $mdconf

more $mdconf

## test stop/start

mdadm -S $md

cat /proc/mdstat

mdadm -A -s -a  ## /etc/init.d/mdadm-raid start

cat /proc/mdstat

## change konfig (final)

cp -p $fstab $fstab.old

cat $fstab.old | sed "s:$pd1:$md:" > $fstab

diff $fstab.old $fstab

</code></pre>

h2. change harddrive

https://wiki.hetzner.de/index.php/Festplattenaustausch_im_Software-RAID