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Improve mdadm page

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Gauthier Provost 2018-07-29 23:32:52 +08:00
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@ -10,9 +10,26 @@ In this guide, we will show how to create different RAID configurations :
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 find to identify storage drives that you will be using to compose your RAID array:
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
@ -34,15 +51,15 @@ As you can see above, we have four drives without a filesystem, each of 1.8TB in
!!! note
To avoid any confusion at identifying the right drive, start Helios4 without any type of USB storage connected to it.
## Create RAID 1 Array
## Create Array
### Step 1 - Create the array
### Create RAID 1 Array
To create a RAID 1 array with 2x drives, pass them in 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:
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:
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
@ -70,9 +87,53 @@ Output
unused devices: <none>
As you can see in the first 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.
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.
### Step 2 - Create and Mount the Filesystem
### 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:
@ -100,9 +161,9 @@ Output
The new filesystem is mounted and accessible.
### Step 3 - Save the Array Layout
## Save the Array Layout
To make sure that the array is reassembled automatically at boot, we will have to adjust the /etc/mdadm/mdadm.conf file. You can automatically scan the active array and append the file by typing:
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
@ -114,51 +175,7 @@ Add the new filesystem mount options to the /etc/fstab file for automatic mounti
echo '/dev/md0 /mnt/md0 ext4 defaults,nofail,discard 0 0' | sudo tee -a /etc/fstab
**Your RAID 1 array should now automatically be assembled and mounted each boot!**
## Create RAID 6 Array
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 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 : [raid6] [raid5] [raid4] [linear] [multipath] [raid0] [raid1] [raid10]
md0 : active raid6 sdd[3] sdc[2] sdb[1] sda[0]
209584128 blocks super 1.2 level 6, 512k chunk, algorithm 2 [4/4] [UUUU]
[>....................] resync = 0.6% (668572/104792064) finish=10.3min speed=167143K/sec
unused devices: <none>
As you can see in the first 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.
Then refer to [Step2](#step-2-create-and-mount-the-filesystem) and [Step3](#step-3-save-the-array-layout) of the RAID1 section.
## Create RAID 10 Array
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 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 : [raid6] [raid5] [raid4] [linear] [multipath] [raid0] [raid1] [raid10]
md0 : active raid10 sdd[3] sdc[2] sdb[1] sda[0]
209584128 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
[===>.................] resync = 18.1% (37959424/209584128) finish=13.8min speed=206120K/sec
unused devices: <none>
As you can see in the first 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.
Then refer to [Step2](#step-2-create-and-mount-the-filesystem) and [Step3](#step-3-save-the-array-layout) of the RAID1 section.
**Your RAID array should now automatically be assembled and mounted each boot!**
## Reset Existing RAID Devices
@ -172,8 +189,8 @@ Find the active arrays in the /proc/mdstat file by typing:
Output
Personalities : [raid0] [linear] [multipath] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid0 sdc[1] sdd[0]
209584128 blocks super 1.2 512k chunks
md0 : active raid6 sdd[3] sdc[2] sdb[1] sda[0]
3906766848 blocks super 1.2 level 6, 512k chunk
unused devices: <none>
@ -194,9 +211,13 @@ Output
NAME SIZE FSTYPE TYPE MOUNTPOINT
sda 1.8T linux_raid_member disk
└─md0 1.8T ext4 raid1 /mnt/md0
└─md0 3.7T ext4 raid6
sdb 1.8T linux_raid_member disk
└─md0 1.8T ext4 raid1 /mnt/md0
└─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
@ -210,6 +231,8 @@ After discovering the devices used to create an array, zero their superblock to
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: