Linux disk management

Feb 2, 2020
linux disk raid

Linux disk management

Install raid and logical volumes on slackware 14.0

Scenario: Installing slackware 14.0 with raid and logical volumes on two hard disk (16GB)).
/ will be set on raid1, /home will be set on logical volume (raid1),/tmp and swap will be set on logical volumes (raid0).
Setup the sda with sda1 12gb, sda2 2gb, sda3 2gb .All with fd partition and sda1 bootable.

sfdisk -d /dev/sda | sfdisk /dev/sdb  (will copy partition to second hdd)
mdadm --create /dev/md0 --level=1 --raid-device=2 /dev/sd[ab]1
mdadm --create /dev/md1 --level=0 --raid-device=2 /dev/sd[ab]2
mdadm --create /dev/md2 --level=1 --raid-device=2 /dev/sd[ab]3
pvcreate /dev/md1
pvcreate /dev/md2
vgcreate raid0_vg0 /dev/md1
vgcreate raid1_vg1 /dev/md2
lvcreate -L2000M -nslackware_home raid1_vg1
lvcreate -L2000M -nswap raid0_vg0
lvcreate -L2000M -nslackware_tmp raid0_vg0
vgchange -a y raid0_vg0
vgchange -a y raid1_vg1

Continue install but donot add swap from installation menu

/dev/md0   /
/dev/raid0_vg0/slackware_tmp    /tmp
/dev/raid1_vg1/slackware_home   /home

Exit install but donot reboot

mdadm -D --scan >> /mnt/etc/mdadm.conf
less /mnt/etc/mdadm.conf
chroot /mnt
mdadm --monitor --daemonise /dev/md[0-9] > /var/run/mdadm

/etc/lilo.conf boot=/dev/md0

lilo -v
mkswap /dev/raid0_vg0/swap

/etc/fstab —> check if mount points are fine and add swap

/dev/raid0_vg0/swap     swap    swap    defaults        0   0

reboot

How to remove RAID devices

If the array is mounted, unmount the array before proceeding

df -kh
umount /dev/md0

Note the devices that make-up the array mdadm --detail /dev/md0
Stop the array mdadm -S /dev/md0
Zero out each of the superblock’s of the devices that belongs to the RAID array

mdadm --zero-superblock /dev/sdb1
mdadm --zero-superblock /dev/sdc1

Remove the DEVICE and ARRAY entry’s associated with the array from /etc/mdadm.conf
Remove the array from /etc/fstab

Create a new RAID array

mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1
mdadm --detail --scan >> /etc/mdadm.conf

Remove a disk from an array

mdadm --fail /dev/md0 /dev/sda1
mdadm --remove /dev/md0 /dev/sda1

Add a disk to an existing array mdadm --add /dev/md0 /dev/sdb1
Verifying the status of the RAID arrays cat /proc/mdstat or mdadm --detail /dev/md0
Stop and delete a RAID array

mdadm --stop /dev/md0
mdadm --remove /dev/md0
mdadm --zero-superblock /dev/sda