LINUX > gérer un système RAID

RAID-1

Préparation des disques

Avant tout, il font démounter les disques durs.

 

lsblk

 

NAME            MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda               8:0    0 465,8G  0 disk
├─sda1            8:1    0   500M  0 part
└─sda2            8:2    0 465,3G  0 part /media/mondisque
sdb               8:16   0 465,8G  0 disk
├─sdb1            8:17   0   100M  0 part
└─sdb2            8:18   0 465,7G  0 part
sdc               8:32   0 119,2G  0 disk
├─sdc1            8:33   0 111,5G  0 part /
└─sdc5            8:37   0   7,8G  0 part [SWAP]

 

Par exemple, si le RAID1 comporte les disque sda et sdb, il faut démounter /media/mondisque :

 

sudo umount /media/mondisque

 

Puis, formater en bas niveau :

 

sudo dd if=/dev/zero of=/dev/sdb bs=512 count=1

 

1+0 records in
1+0 records out
512 bytes copied, 0,00108261 s, 473 kB/s

 

bs=512 et count=1 permet de ne supprimer que le premier et dernier blocs, ce qui évite de tout effecer et gagner beaucoup de temps.

configuration du RAID1

sudo apt-get install mdadm

 

Puis :

 

sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda /dev/sdb

mdadm: array /dev/md0 started.

 

/dev/md0 nom du RAID

--level=1 niveau du RAID.

--raid-devices=2 nombre de périphériques dans le RAID

 

Pour voir la progression de la création du RAID :

 

watch cat /proc/mdstat

 

Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdb[1] sda[0]
488255488 blocks super 1.2 [2/2] [UU]
[>....................]  resync =  1.2% (6091648/488255488) finish=107.8min speed=74518K/sec
bitmap: 4/4 pages [16KB], 65536KB chunk

unused devices: <none>

 

Ensuite, créer un système de fichier sur la nouvelle grappe du RAID créé :

 

sudo mkfs.ext4 /dev/md0

 

mke2fs 1.42.13 (17-May-2015)
Creating filesystem with 122063872 4k blocks and 30523392 inodes
Filesystem UUID: ********-f910-4419-b352-d729a05587d4
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 102400000

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

 

Créér un point de montage :

 

sudo mkdir -p /mnt/raid1

 

Ajouter la configuration du RAID dans /etc/mdadm/mdadm.conf :

 

sudo mdadm --detail --scan | sudo tee -a /etc/mdadm/mdadm.conf

 

Ajouter le montage automatique dans /etc/fstab :

 

/dev/md0   /mnt/raid1   ext4   defaults   0 2

 

Le premier zéro : si égal à 1, l’OS will use DUMP utility to make backups of the file system. If set to 0, no backups will be made.

Le second zéro disables fsck utility on the selected volume during reboots. In this field 0, 1 or 2 can be set. 1 should be specified for the root file system, and 2 for other file systems.

Enlever une grappe

désactiver la grappe :

 

$ sudo mdadm --stop /dev/md0

 

puis, effacer les superbloc de chaque disque :

 

sudo mdadm --zero-superblock /dev/sda
sudo mdadm --zero-superblock /dev/sdb

 

Puis enlever la grappe depuis mdadm:

 

sudo mdadm --remove /dev/md0

 

Puis, on vérifie :

 

sudo mdadm --detail /dev/md0

 

/dev/md0:
Version : 1.2
Creation Time : Thu Dec 15 14:55:34 2016
Raid Level : raid1
Array Size : 1047552 (1023.17 MiB 1072.69 MB)
Used Dev Size : 1047552 (1023.17 MiB 1072.69 MB)
Raid Devices : 2
Total Devices : 1
Persistence : Superblock is persistent

Update Time : Mon Dec 19 17:19:31 2016
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0

Name : LinuxMint18:1  (local to host LinuxMint18)
UUID : b16a3861:********:3abd06ba:7346e91d
Events : 63

Number   Major   Minor   RaidDevice State
0       8       48        0      active sync   /dev/sdd
2       0        0        2      removed

 

On peut retirer le disque physique.

 

Pour vérifier si un disque est défaillant :

 

sudo mdadm /dev/md127 --fail /dev/sde

 

Pour enlever un disque :

 

$ sudo mdadm /dev/md127 --remove /dev/sde

 

ajouter un disque dans une grappe

lsblk

 

NAME    MAJ:MIN RM  SIZE RO TYPE  MOUNTPOINT
sda       8:0    0   20G  0 disk
├─sda1    8:1    0   19G  0 part  /
├─sda2    8:2    0    1K  0 part
└─sda5    8:5    0 1022M  0 part  [SWAP]
sdb       8:16   0    8G  0 disk
└─md126   9:126  0    8G  0 raid1 /mnt/raiddisk1
sdc       8:32   0    8G  0 disk
└─md126   9:126  0    8G  0 raid1 /mnt/raiddisk1
sdd       8:48   0    1G  0 disk
└─md127   9:127  0 1023M  0 raid1 /mnt/raiddisk2
sde       8:80   0    1G  0 disk

 

To add this new hard drive to the array:

 

$ sudo mdadm /dev/md127 --add /dev/sde

 

The previous command adds the new sde hard disk to the md127 array:

 

$ lsblk

 

NAME    MAJ:MIN RM  SIZE RO TYPE  MOUNTPOINT
sda       8:0    0   20G  0 disk
├─sda1    8:1    0   19G  0 part  /
├─sda2    8:2    0    1K  0 part
└─sda5    8:5    0 1022M  0 part  [SWAP]
sdb       8:16   0    8G  0 disk
└─md126   9:126  0    8G  0 raid1 /mnt/raiddisk1
sdc       8:32   0    8G  0 disk
└─md126   9:126  0    8G  0 raid1 /mnt/raiddisk1
sdd       8:48   0    1G  0 disk
└─md127   9:127  0 1023M  0 raid1 /mnt/raiddisk2
sde       8:64   0    1G  0 disk
└─md127   9:127  0 1023M  0 raid1 /mnt/raiddisk2

 

—  —  —

 

Setting up Raid 1 sur Linux Mint XFCE :

 

Effacer les données sur les disques

 

sudo dd if=/dev/zero of=/dev/sda bs=1048576

sudo dd if=/dev/zero of=/dev/sdb bs=1048576

 

the DD command will clean the hard drives off of anything.

 

cfdisk /dev/sda

Create a new 500 MB partition or 1 gig partition at the beginning

Move the selection bar into the Free Space

Create a new partition with the remaining space

Change the type of this partition to FD.

Write the changes

Quit cfdisk

 

cfdisk /dev/sdb

Create a new 500 MB partition or 1 gig at the beginning

Move the selection bar into the Free Space

Create a new partition with the remaining space

Change the type of this partition to FD.

Write the changes

Quit cfdisk

 

cfdisk -P s /dev/sda

To get last sector #

 

 

mdadm --create /dev/md0 --level=raid1 --raid-devices=2 /dev/sda2 /dev/sdb2

mkfs.ext3 /dev/md0

ln /dev/md0 /dev/sde

mkfs.ext3 /dev/sda1

mkfs.ext3 /dev/sdb1

 

That command will copy the boot partition over to the sdb drive so if sda goes down, the system will still start up.

Install Debian based Linux

Start the installer, it has an icon on the desktop. When you get to the ‘Allocate drive space’ dialog, choose the ‘Specify partitions manually’ option. Click the /dev/sda1 partition, choose ‘Change…’ and fill out the following options:

Use as: Ext3 journaling file system Format the partition: No (do not check the checkmark) Mount point: /boot

Click the /dev/md0 partition, choose ‘Change’, and fill it out like this:

Use as: Ext3 journaling file system Format the partition: No (do not check the checkmark Mount point: /

There’s also a dropdown for ‘Device for boot loader installation’. Make sure that /dev/sda is selected there. Click the ‘Install Now’ button, and ‘Continue’ on any confirmation dialogs you might get. Fill out the rest of the install questions and sit back while the OS installs itself.

 

When the installer is done, do*not*reboot the system yet (choose ‘Continue testing’). Go back to your terminal screen and prepare the boot partition:

 

mkdir /raid

mount /dev/md0 /raid

mount /dev/sda1 /raid/boot

mount --bind /dev /raid/dev

mount -t devpts devpts /raid/dev/pts

mount -t proc proc /raid/proc

mount -t sysfs sysfs /raid/sys

mount -o bind /etc/resolv.conf /raid/etc/resolv.conf

chroot /raid

apt-get install mdadm

 

nano /etc/mdadm/mdadm.conf and remove the / from between md and the 0

hit control X and save the file

then type mdadm --assemble /dev/md0

 

puis taper exit:

puis copier the boot partition over to the sdb drive so if sda goes down, the system will still start up.

dd if=/dev/sda of=/dev/sdb count=(last sector # here)

 

Reboot and it should boot up to the OS with no problem

 

Checking the RAID

A useful command that will tell you the status of the RAID is*cat /proc/mdstat

It’s output is something like:

md0 : active raid1 sda2[0] sdb2[1] 62468672 blocks [2/2] [UU]

The UU means both RAID1 components are ‘Up’. If one disappears, it’s ‘U’ will change to and underscore (‘_’).

 

Most of the info was taken from

http://www.michielovertoom.com/linux/ubuntu-software-raid/

 

With updates/modifications from me (like size of boot partition)

 

I got this working in a VM setting after toying with it for 2 days and doing loads of research. Figured it might help someone. Even if it’s just to learn how.

 

PS: Just got this working on a dell optiplex 330 with 2 500 gig hard drives and everything works with linux mint 17 xfce