Common RAID levels explained

  • RAID 0 – Disk Striping

– Used for the storage of noncritical items but which requires fast read-write.
– Does not have parity (parity is about checking whether the data has been lost or overwritten on transition)
– Does not have redundancy or fault tolerance. i.e., when the drive dies, the data is lost.

  • RAID 1 – Disk Mirroring

– Used usually for OS, SQL Engine etc. installation
– Two or more disks used to write data and is in parallel
– High performance
– High availability
– No data loss on disk failure

  • RAID 2
  • RAID 3
  • RAID 4
  • RAID 5 – Striping with Parity

Requires 3-16 drives
No data loss on disk failure
Read is faster but write can be slower
Failures can impact throughput

  • RAID 6 – Striping with Double Parity

Requires min. 4 drives.
Two drives are used for storing parity data
Read is faster but write can be slower than RAID 5
More secure than RAID 5

  • RAID 7
  • RAID 10 / RAID 1+0 – Striped Set of Mirrors

10 means combining 1 and 0, and not “ten”
Combines disk mirroring and disk striping
Requires minimum 4 disks
Best choice for I/O intensive applications

Note: Blog incomplete. Will be updated.
Note: My learning notes, source: Internet