RAID.md (1757B)
1 # RAID 2 3 **Source:** Wikipedia :\ 4 5 **Definition:** Redundant Array of Independent Disks (RAID) configurations are storage device configurations that implement at least one of the following: striping, mirroring, parity. 6 7 NOTE: There are additional RAID levels, but they are largely unused. 8 9 ## RAID 0 10 11 - [x] Striping 12 - [ ] Mirroring 13 - [ ] Parity 14 15 RAID 0 is quite dangerous. While it benefits from striping and has no overhead cost for mirroring or parity, the loss of one drive is capable of destroying all data given that data is striped across all disks to improve IO speed. 16 17 ## RAID 1 18 19 - [ ] Striping 20 - [x] Mirroring 21 - [ ] Parity 22 23 RAID 1 pairs drives for mirroring. This results in decent read performance and reliability, but poor write performance and storage capacity. 24 25 ## RAID 5 26 27 - [x] Striping 28 - [ ] Mirroring 29 - [x] Parity 30 31 RAID 5 uses striping with distributed parity. This requires all but one drives to be able to operate. Additionally, RAID 5 requires at least three disks. This is a popular approach with three disks. 32 33 ## RAID 6 34 35 - [x] Striping 36 - [ ] Mirroring 37 - [x] Parity 38 39 RAID 6 is basically RAID 5 except it has an additional parity block. This requires four disks, but can remain functional even if two disks fail. 40 41 ## RAID 10 42 43 - [x] Striping 44 - [x] Mirroring 45 - [ ] Parity 46 47 RAID 10 (also referred to as RAID 1+0) combines mirroring and striping for reliability and performance. RAID 10 requires at least four disks and works by striping across pairs. This results in a 50% decrease in storage capacity w.r.t. RAID 0, but can survive one disk failure from each pair before any data is lost. Once data is lost, it is likely all data will be lost. While the worst case for this means it can only survive one failure, this is often not the case.