raid1 on existing filesystem -> Example
Existing filesystem is on /dev/sda
/dev/root /
/dev/sda5 /var
/dev/sda6 /usr
/dev/sda8 /home
Connect new disk (for example /dev/sdb)
Copy partition structure from sda to sdc:
sfdisk -d /dev/sda | sfdisk /dev/sdb
or if disk has differ size
create the same size ( or bigger) partitions on sdb
end change type for fd (Linux raid autodetect)
change disk’s blkid
tune2fs -U random /dev/sdbNext, create the single-disk RAID-1 array. Note the “missing” keyword is specified as one of our devices. We are going to fill this missing device later.
mdadm --create /dev/md0 --level=1 --raid-devices=2 missing /dev/sdb1
or
mdadm --create /dev/md0 --metadata=0.90 --level=1 --raid-devices=2 missing /dev/sdb1
and for other partitions
mdadm --create /dev/md1 --metadata=0.90 --level=1 --raid-devices=2 missing /dev/sdb5
mdadm --create /dev/md2 --metadata=0.90 --level=1 --raid-devices=2 missing /dev/sdb6
mdadm --create /dev/md3 --metadata=0.90 --level=1 --raid-devices=2 missing /dev/sdb7
cat /proc/mdstat shows just created raid
Use the file system of your preference here. I'll use ext4 for this guide.
mkfs -t ext4 -j -L RAID-ONE /dev/md0
mkfs -t ext4 -j -L RAID-ONE /dev/md1
mkfs -t ext4 -j -L RAID-ONE /dev/md2
mkfs -t ext4 -j -L RAID-ONE /dev/md3
Make a file system on the swap partition:
mkswap -L NEW-SWAP /dev/sdb2
The new RAID-1 array is ready to start accepting data! So now we need to mount the array, and copy everything from the old system to the new system
mkdir /tmp/md0 /tmp/md1 /tmp/md2 /tmp/md3
mount /dev/md0 /tmp/md0 mount /dev/md1 /tmp/md1
mount /dev/md2 /tmp/md2
mount /dev/md3 /tmp/md3
rsync -avxHAXS --delete --progress /home/ /tmp/md3
rsync -avxHAXS --delete --progress /var/ /tmp/md2
rsync -avxHAXS --delete --progress /usr/ /tmp/md1
rsync -avxHAXS --delete --progress / /tmp/md0
edit /etc/fstab and change mounting points to appropriate /dev/md0 .. /dev/md3
and add line:
/dev/sdb2 swap swap defaults 0 0
reboot with opition root=/dev/md0 (where my root filesystem was located).
telinit 1 ?
First, open /dev/sda with fdisk and change all the partittions you want to have added to the array to type fd – linux raid autodetection.
Then, for each degraded array, add the appropriate non-array device to it:
mdadm /dev/md0 -a /dev/sda1
(wait for finish recovery)
(umount/dev/sda5)
mdadm /dev/md1 -a /dev/sda5
(wait for finish recovery)
umount/dev/sda6
mdadm /dev/md2 -a /dev/sda6
(wait for finish recovery)
umount/dev/sda8
mdadm /dev/md3 -a /dev/sda8
(wait for finish recovery)
Ensure your /etc/lilo.conf has the correct setup:
boot=/dev/md0 raid-extra-boot=mbr-only
root=/dev/md0
and type:
lilo
LILO will write boot information to each of the individual raid devices boot sectors, so if either /boot or your root partition are on failed disks, you’ll still be able to boot.
Create /etc/mdadm/mdadm.conf.
in /etc/mdadm/mdadm.conf put line:
DEVICE /dev/sda* /dev/sdb*
and WHEN ALL PARTITIONS ARE REBUILDED run:
mdadm --detail --scan >> /etc/mdadm.conf