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====How to setup RAID-0 on Debian====


The RAID 0 array works by breaking up data into chunks and striping it across the available disks. This means that each disk contains a portion of the data and that multiple disks will be referenced when retrieving information.

  * Requirements: minimum of 2 storage devices
  * Primary benefit: Performance
  * Make sure that you have functional backups. A single device failure will destroy all data in the array.


Identify the disks you want to use

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

say you see sda, sdb and sdc. SDA is possibly divided in sda1 and sda2, meaning that this disk is in use. If the other are just SDB and SDC these should be the disk you are aiming for. 

  NAME     SIZE FSTYPE TYPE MOUNTPOINT
  sdb      100G        disk
  sdc      100G        disk
  sda       25G        disk 
  ├─sda1  24.9G ext4   part /
  ├─sda14    4M        part 
  └─sda15  106M vfat   part /boot/efi


Create the Array

   sudo mdadm --create --verbose /dev/md0 --level=0 --raid-devices=2 /dev/sda /dev/sdb

check if it is crated successful by doing a

   cat /proc/mdstat

The output should look something like:

  Personalities : [raid0] 
  md0 : active raid0 sdb[1] sdc[0]
      209584128 blocks super 1.2 512k chunks
  
  unused devices: <none>

Next you have to create a filesystem to use your array

  sudo mkfs.ext4 -F /dev/md0

Note that MD0 is your array sdb1 and sdc2 together. 

Now create a mount point on your system like /mnt/md0 or /datastore

   sudo mkdir -p /mnt/md0

After that you are able to mount the new array

   sudo mount /dev/md0 /mnt/md0

Check if it is available by doing:

  df -h -x devtmpfs -x tmpfs

To make sure that the array is reassemble every time you boot your system you need to set your configuration of your array in a file /etc/mdadm/mdadm.conf.

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

Next update the initramfs by doing a

  sudo update-initramfs -u

If you like to auto mount your array at boot you need a entry in your fstab. Edit your fstab like this

  echo '/dev/md0 /mnt/md0 ext4 defaults,nofail,discard 0 0' | sudo tee -a /etc/fstab


That's all, enjoy.


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