forum.zelfbouwaudio.nl

ds23man schreef:

Trouwens, als je linux gebruikt moet je de SATA in de BIOS op AHCI zetten en software raid gebruiken. Dit moet ook trouwens als je van de ODD wil booten.

https://www.digitalocean.com/community/tutorials/how-to-create-raid-arrays-with-mdadm-on-ubuntu-16-04 schreef:

Creating a RAID 1 Array

The RAID 1 array type is implemented by mirroring data across all available disks. Each disk in a RAID 1 array gets a full copy of the data, providing redundancy in the event of a device failure.

Requirements: minimum of 2 storage devices
Primary benefit: Redundancy
Things to keep in mind: Since two copies of the data are maintained, only half of the disk space will be usable

Identify the Component Devices

To get started, find the identifiers for the raw disks that you will be using:

lsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT

Output
NAME SIZE FSTYPE TYPE MOUNTPOINT
sda 100G disk
sdb 100G disk
vda 20G disk
├─vda1 20G ext4 part /
└─vda15 1M part

As you can see above, we have two disks without a filesystem, each 100G in size. In this example, these devices have been given the /dev/sda and /dev/sdb identifiers for this session. These will be the raw components we will use to build the array.
Create the Array

To create a RAID 1 array with these components, 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:

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

If the component devices you are using are not partitions with the boot flag enabled, you will likely be given the following warning. It is safe to type y to continue:

Output
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 104792064K
Continue creating array? y

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 : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdb[1] sda[0]
104792064 blocks super 1.2 [2/2] [UU]
[====>................] resync = 20.2% (21233216/104792064) finish=6.9min speed=199507K/sec

unused devices: <none>

As you can see in the first highlighted line, the /dev/md0 device has been created in the RAID 1 configuration using the /dev/sda and /dev/sdb devices. The second highlighted line shows the progress on the mirroring. You can continue the guide while this process completes.
Create and Mount the Filesystem

Next, 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/vda1 20G 1.1G 18G 6% /
/dev/md0 99G 60M 94G 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 adjust the /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, or initial RAM file system, so that the array will be available during the early boot process:

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 1 array should now automatically be assembled and mounted each boot.

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