259 lines
10 KiB
Markdown
259 lines
10 KiB
Markdown
The **mdadm** utility can be used to create and manage storage arrays using Linux's software RAID capabilities.
|
|
|
|
In this guide, we will show how to create different RAID configurations :
|
|
|
|
* RAID1 (for 2x HDD)
|
|
* RAID6 (for 4x HDD)
|
|
* RAID10 (for 4x HDD)
|
|
|
|
## Install mdadm
|
|
|
|
sudo apt-get install mdadm
|
|
|
|
### Fix mdadm
|
|
|
|
You might see the following error message in your boot messages *"mdadm: initramfs boot message: /scripts/local-bottom/mdadm: rm: not found"*
|
|
|
|
To fix this minor issue simply edit the *mdadm* hook script of initramfs:
|
|
|
|
sudo nano /usr/share/initramfs-tools/hooks/mdadm
|
|
|
|
Add **copy_exec /bin/rm /bin** after the following lines:
|
|
|
|
copy_exec /sbin/mdadm /sbin
|
|
copy_exec /sbin/mdmon /sbin
|
|
|
|
Then update initramfs:
|
|
|
|
sudo update-initramfs -u
|
|
|
|
## Identify you Storage Drives
|
|
|
|
To get started, you will need first to identify the storage drives that you will use to compose your RAID array:
|
|
|
|
lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT
|
|
|
|
Output
|
|
|
|
NAME SIZE FSTYPE TYPE MOUNTPOINT
|
|
sda 1.8T disk
|
|
sdb 1.8T disk
|
|
sdc 1.8T disk
|
|
sdd 1.8T disk
|
|
mmcblk0 14.9G disk
|
|
└─mmcblk0p1 14.7G ext4 part /
|
|
zram0 50M disk /var/log
|
|
zram1 504.4M disk [SWAP]
|
|
zram2 504.4M disk [SWAP]
|
|
|
|
As you can see above, we have four drives without a filesystem, each of 1.8TB in size. So our drives are /dev/sda, /dev/sdb, /dev/sdc and /dev/sdd.
|
|
|
|
!!! note
|
|
To avoid any confusion at identifying the right drive, start Helios4 without any type of USB storage connected to it.
|
|
|
|
## Create Array
|
|
|
|
### Create RAID 1 Array
|
|
|
|
To create a RAID 1 array with 2x drives, pass them to the mdadm --create command. You will have to specify the device name you wish to create (**/dev/md0** in our case), the RAID level, and the number of devices:
|
|
|
|
sudo mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sda /dev/sdb
|
|
|
|
If the drives you are using are not partitioned with the boot flag enabled, you will likely be given the following warning. It is safe to type **y** to continue:
|
|
|
|
mdadm: Note: this array has metadata at the start and
|
|
may not be suitable as a boot device. If you plan to
|
|
store '/boot' on this device please ensure that
|
|
your boot-loader understands md/v1.x metadata, or use
|
|
--metadata=0.90
|
|
mdadm: size set to 1953383488K
|
|
mdadm: automatically enabling write-intent bitmap on large array
|
|
Continue creating array? y
|
|
mdadm: Defaulting to version 1.2 metadata
|
|
mdadm: array /dev/md0 started.
|
|
|
|
|
|
The mdadm tool will start to mirror the drives. This can take some time to complete, but the array can be used during this time. You can monitor the progress of the mirroring by checking the /proc/mdstat file:
|
|
|
|
cat /proc/mdstat
|
|
|
|
Output
|
|
|
|
Personalities : [raid1]
|
|
md0 : active raid1 sdb[1] sda[0]
|
|
1953383488 blocks super 1.2 [2/2] [UU]
|
|
[>....................] resync = 0.9% (19054272/1953383488) finish=213.6min speed=150885K/sec
|
|
bitmap: 15/15 pages [60KB], 65536KB chunk
|
|
|
|
unused devices: <none>
|
|
|
|
As you can see in the second line, the /dev/md0 device has been created with the RAID 1 configuration using the /dev/sda and /dev/sdb devices. The fourth line shows the progress on the mirroring. You can continue the guide while this process completes.
|
|
|
|
### Create RAID 6 Array
|
|
|
|
To create a RAID 6 array with 4x drives, pass them to the mdadm --create command. You will have to specify the device name you wish to create (**/dev/md0** in our case), the RAID level, and the number of devices:
|
|
|
|
sudo mdadm --create --verbose /dev/md0 --level=6 --raid-devices=4 /dev/sda /dev/sdb /dev/sdc /dev/sdd
|
|
|
|
The mdadm tool will start to configure the array (it actually uses the recovery process to build the array for performance reasons). This can take some time to complete, but the array can be used during this time. You can monitor the progress of the mirroring by checking the /proc/mdstat file:
|
|
|
|
cat /proc/mdstat
|
|
|
|
Output
|
|
|
|
Personalities : [raid1] [raid0] [raid6] [raid5] [raid4] [raid10]
|
|
md0 : active raid6 sdd[3] sdc[2] sdb[1] sda[0]
|
|
3906766848 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU]
|
|
[>....................] resync = 0.3% (7171152/1953383424) finish=471.0min speed=68866K/sec
|
|
bitmap: 15/15 pages [60KB], 65536KB chunk
|
|
|
|
unused devices: <none>
|
|
|
|
As you can see in the second line, the /dev/md0 device has been created with the RAID 6 configuration using the /dev/sda, /dev/sdb, /dev/sdc and /dev/sdd devices. The fourth line shows the progress on the mirroring. You can continue the guide while this process completes.
|
|
|
|
### Create RAID 10 Array
|
|
|
|
To create a RAID 10 array with 4x drives, pass them to the mdadm --create command. You will have to specify the device name you wish to create (**/dev/md0** in our case), the RAID level, and the number of devices:
|
|
|
|
sudo mdadm --create --verbose /dev/md0 --level=10 --raid-devices=4 /dev/sda /dev/sdb /dev/sdc /dev/sdd
|
|
|
|
The mdadm tool will start to configure the array (it actually uses the recovery process to build the array for performance reasons). This can take some time to complete, but the array can be used during this time. You can monitor the progress of the mirroring by checking the /proc/mdstat file:
|
|
|
|
cat /proc/mdstat
|
|
|
|
Output
|
|
|
|
Personalities : [raid1] [raid0] [raid6] [raid5] [raid4] [raid10]
|
|
md0 : active raid10 sdd[3] sdc[2] sdb[1] sda[0]
|
|
3906766848 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
|
|
[>....................] resync = 0.5% (20708608/3906766848) finish=305.0min speed=212294K/sec
|
|
bitmap: 30/30 pages [120KB], 65536KB chunk
|
|
|
|
unused devices: <none>
|
|
|
|
As you can see in the second line, the /dev/md0 device has been created with the RAID 10 configuration using the /dev/sda, /dev/sdb, /dev/sdc and /dev/sdd devices. The fourth line shows the progress on the mirroring. You can continue the guide while this process completes.
|
|
|
|
## Create and Mount the Filesystem
|
|
|
|
Create a filesystem on the array:
|
|
|
|
sudo mkfs.ext4 -F /dev/md0
|
|
|
|
Create a mount point to attach the new filesystem:
|
|
|
|
sudo mkdir -p /mnt/md0
|
|
|
|
You can mount the filesystem by typing:
|
|
|
|
sudo mount /dev/md0 /mnt/md0
|
|
|
|
Check whether the new space is available by typing:
|
|
|
|
df -h -x devtmpfs -x tmpfs
|
|
|
|
Output
|
|
|
|
Filesystem Size Used Avail Use% Mounted on
|
|
/dev/mmcblk0p1 15G 842M 14G 6% /
|
|
/dev/zram0 49M 784K 45M 2% /var/log
|
|
/dev/md0 1.8T 77M 1.7T 1% /mnt/md0
|
|
|
|
|
|
The new filesystem is mounted and accessible.
|
|
|
|
## Save the Array Layout
|
|
|
|
To make sure that the array is reassembled automatically at boot, we will have to modify /etc/mdadm/mdadm.conf file. You can automatically scan the active array and append the file by typing:
|
|
|
|
sudo mdadm --detail --scan | sudo tee -a /etc/mdadm/mdadm.conf
|
|
|
|
Afterwards, you can update the initramfs, so that the array will be available during the early boot stage:
|
|
|
|
sudo update-initramfs -u
|
|
|
|
Add the new filesystem mount options to the /etc/fstab file for automatic mounting at boot:
|
|
|
|
echo '/dev/md0 /mnt/md0 ext4 defaults,nofail,discard 0 0' | sudo tee -a /etc/fstab
|
|
|
|
**Your RAID array should now automatically be assembled and mounted at each boot!**
|
|
|
|
## Reset Existing RAID Devices
|
|
|
|
!!! warning
|
|
This process will completely destroy the array and any data written to it. Make sure that you are operating on the correct array and that you have copied off any data you need to retain prior to destroying the array.
|
|
|
|
Find the active arrays in the /proc/mdstat file by typing:
|
|
|
|
cat /proc/mdstat
|
|
|
|
Output
|
|
|
|
Personalities : [raid0] [linear] [multipath] [raid1] [raid6] [raid5] [raid4] [raid10]
|
|
md0 : active raid6 sdd[3] sdc[2] sdb[1] sda[0]
|
|
3906766848 blocks super 1.2 level 6, 512k chunk
|
|
|
|
unused devices: <none>
|
|
|
|
Unmount the array from the filesystem:
|
|
|
|
sudo umount /dev/md0
|
|
|
|
Then, stop and remove the array by typing:
|
|
|
|
sudo mdadm --stop /dev/md0
|
|
sudo mdadm --remove /dev/md0
|
|
|
|
Find the devices that were used to build the array with the following command:
|
|
|
|
lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT
|
|
|
|
Output
|
|
|
|
NAME SIZE FSTYPE TYPE MOUNTPOINT
|
|
sda 1.8T linux_raid_member disk
|
|
└─md0 3.7T ext4 raid6
|
|
sdb 1.8T linux_raid_member disk
|
|
└─md0 3.7T ext4 raid6
|
|
sdc 1.8T linux_raid_member disk
|
|
└─md0 3.7T ext4 raid6
|
|
sdd 1.8T linux_raid_member disk
|
|
└─md0 3.7T ext4 raid6
|
|
mmcblk0 14.9G disk
|
|
└─mmcblk0p1 14.7G ext4 part /
|
|
zram0 50M disk /var/log
|
|
zram1 504.4M disk [SWAP]
|
|
zram2 504.4M disk [SWAP]
|
|
|
|
!!! important
|
|
Keep in mind that the /dev/sd* names can change any time you reboot! Check them every time to make sure you are operating on the correct devices.
|
|
|
|
After discovering the devices used to create an array, zero their superblock to reset them to normal:
|
|
|
|
sudo mdadm --zero-superblock /dev/sda
|
|
sudo mdadm --zero-superblock /dev/sdb
|
|
sudo mdadm --zero-superblock /dev/sdc
|
|
sudo mdadm --zero-superblock /dev/sdd
|
|
|
|
You should remove any of the persistent references to the array. Edit the /etc/fstab file and comment out or remove the reference to your array:
|
|
|
|
```bash
|
|
sudo nano /etc/fstab
|
|
|
|
# /dev/md0 /mnt/md0 ext4 defaults,nofail,discard 0 0
|
|
```
|
|
|
|
Also, comment out or remove the array definition from the /etc/mdadm/mdadm.conf file:
|
|
|
|
```bash
|
|
sudo nano /etc/mdadm/mdadm.conf
|
|
|
|
# ARRAY /dev/md0 metadata=1.2 name=mdadmwrite:0 UUID=7261fb9c:976d0d97:30bc63ce:85e76e91
|
|
```
|
|
|
|
Finally, update the initramfs again:
|
|
|
|
sudo update-initramfs -u
|
|
|
|
At this point, you should be ready to reuse the storage devices individually, or as components of a different array.
|
|
|
|
*Tuto Source: [link](https://www.digitalocean.com/community/tutorials/how-to-create-raid-arrays-with-mdadm-on-ubuntu-16-04)*
|