RAID LevelsRAID 0 | Stripes data evenly across two or more disks. | RAID 1 | Mirrors data on two or more disks. | RAID 2 | Rarely used, Bit-level striping with Hamming code for error correction. | RAID 3 | Rarely used, byte-level striping with a dedicated parity. | RAID 4 | Block-level striping with dedicated parity. | RAID 5 | Block-level striping with distributed parity. | RAID 6 | Block-level striping with double distributed parity. |
Nested RAID LevelsNumber | Description | Efficiency | RAID 01 | Block-level striping, and mirroring without parity | 1/stripes | RAID 10 | Mirroring without parity, and block-level striping | stripes/n | RAID 50 | Block-level striping with distributed parity, and block-level striping | (1-stripes)/n | RAID 60 | Block-level striping with double distributed parity, and block-level striping | (1-2*stripes)/n |
| | Formatting Disks for Use with mdadmDISCLAIMER: PROCEED WITH CAUTION. | MAKE SURE YOU KNOW WHAT DISK YOU ARE OPERATING ON. IT IS VERY EASY TO DO IRREVOCABLE DAMAGE TO YOUR SYSTEM IF YOU DON'T. | 0. Figure out disk location in the file system: | lsblk -o name,size,fstype,type,mountpoint
| 1. Formatting with fdisk | sudo fdisk /dev/sdx
| 2. Navigatng fdisk: just press the following keys when promted to create new linux RAID type primary partition | n , p , 1 , Enter , Enter , t , fd , w
| 3. Repeat steps 1 and 2 for each disk that will be included in new array | sudo fdisk /dev/sdy
| n , p , 1 , Enter , Enter , t , fd , w
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Creating RAID arraysCreate a mirrored array | mdadm --create /dev/md0 --level=1 /dev/sdx1 /dev/sdy1 |
Assembling RAID arraysAssemble an existing array | mdadm --assemble /dev/md0 /dev/sdx1 /dev/sdy1
| mdadm --scan --assemble --uuid=<UUID>
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Resetting Existing RAID DevicesFind the active arrays | cat /proc/mdstat
| Unmount the array | sudo umount /dev/md0
| Stop and remove the array | mdadm --stop /dev/md0
| mdadm --remove /dev/md0
| Find the devices used to build the array | lsblk -o name,fstype,mountpoint
| Zero out the respective superblocks | sudo mdadm --zero-superblock /dev/sdx
| sudo mdadm --zero-superblock /dev/sdy
| Remove persistent references to the array | sudo nano /etc/fstab
| Comment out or remove the reference to the array. | # /dev/md0 /mnt/md0 ext4 defaults,nofail,discard 0 0
| In /etc/mdadm/mdadm.conf comment out or remove the array reference | sudo nano /etc/mdadm/mdadm.conf
| Comment out the reference | # ARRAY /dev/md0 metadata=1.2 name=mdadmwrite:0 UUID=xxxx
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