Ubuntu – Howto Easily Setup RAID 5 with LVM

Some notes for me to follow next time I do it:

1. Install mdadm and S.M.A.R.T. drive monitoring

   # apt-get install mdadm smartmontools

2. Enable smartd

   # vi /etc/defaults/smartmontools

   uncomment the “start_smartd=yes” line

3. Edit smartd config and tell it what drives to monitor

   # vi /etc/smartd.conf

   add these lines to monitor each drive:

   /dev/sdc -a -I 194 -W 4,45,55 -R 5 -m your@email.com
   /dev/sdd -a -I 194 -W 4,45,55 -R 5 -m your@email.com
   /dev/sde -a -I 194 -W 4,45,55 -R 5 -m your@email.com

4. Partition the 3 drives into “Linux Raid Autodetect” partitions:

   # fdisk /dev/sdc

   n (new)
   p (primary)
   1 (1st primary)
   t (change type)
   fd (set type to linux raid autodetect)
   w (write changes and exit fdisk)
   repeat for /dev/sdd and /dev/sde

5. Create the raid 5 array on the 3 drives:

   # mdadm --create /dev/md0 --level=5 -n 3 /dev/sdc1 /dev/sdd1 /dev/sde1

6. Build a new mdadm.conf file, first grab a description of all running raid instances:
   # mdadm --detail --scan
ARRAY /dev/md0 level=raid5 num-devices=3 metadata=00.90 spares=1
  UUID=b144b150:b3b4ff34:2bababc5:c86c0f3a
Then copy and paste this into the /dev/mdadm/mdadm.conf file (remove old default val) so the mdadm.conf file should look something like:

   DEVICE partitions
   CREATE owner=root group=disk mode=0660 auto=yes
   HOMEHOST <system>
   MAILADDR your@email.com
   ARRAY /dev/md0 level=raid5 num-devices=3 metadata=00.90 spares=1 
        UUID=b144b150:b3b4ff34:2bababc5:c86c0f3a (all on 1 line)
   

7. Check status of raid:

   # mdadm --detail /dev/md0

   this shows rebuild state.

8. Initialize the entire md0 raid array for LVM use.

   # pvcreate /dev/md0

9. Create the volume group

   # vgcreate vg1 /dev/md0

10. Create a logical volume (something you can mount – where files are stored) but make it the entire size of the raid 5 array.. first have to find out current size:

    # vgdisplay vg1 | grep "Total PE"
       Total PE              715399
    # lvcreate -l 715399 -n lv1 vg1 /dev/md0
       Logical volume "lv1" created

11. Make the file system on our new lv1 volume:

    # mkfs.reiserfs /dev/vg1/lv1

12. Make the dir where you want to mount array:

    # mkdir /data

13. Add entry to fstab

    # vi /etc/fstab
    /dev/mapper/vg1-lv1  /data      reiserfs auto       0       0

14. Mount the new LVM raid 5 array:

    # mount /data

15. Check it worked:

    # df -h
    /dev/mapper/vg1-lv1   2.7T  202M  2.6T   1% /data

16. Done.

Edit: I have now re-done this without LVM. Click here to see those steps instead.