RAID
RAID
| Level | Characteristics |
| 0 | Stripe Sets w/o parity - can use diff types of drives - 2 or more drives - best performance but no fault-tolerance |
| *1 | Mirroring & Duplexing - 2 sep drives - Best performance and the best fault-tolerance in a multi-user system. |
| 2 | This type uses striping across disks with some disks storing error checking and correcting (ECC) information. It has no advantage over RAID-3. |
| 3 | Parity written to one disk. best for single-user systems with long record applications. |
| *4 | Independent disks with shared parity - high transaction rate and low ratio of ECC (parity) disks to data disks - writes parity across one disk - high efficiency - bad write transaction rate - 3 drive min - one disk parity disk |
| *5 | Striping with parity - 3 drives needed - Read Only efficient - writes parity across multiple disks - greater speed and redundancy |
| 6 | This type is similar to RAID-5 but includes a second parity scheme that is distributed across different drives and thus offers extremely high fault- and drive-failure tolerance. There are few or no commercial examples currently. |
| 7 | This type includes a real-time embedded operating system as a controller, caching via a high-speed bus, and other characteristics of a stand-alone computer. One vendor offers this system. |
| 10 | This type offers an array of stripes in which each stripe is a RAID-1 array of drives. This offers higher performance than RAID-1 but at much higher cost. |
| 53 | This type offers an array of stripes in which each stripe is a RAID-3 array of disks. This offers higher performance than RAID-3 but at much higher cost. |
Mirroring - Same on duplicate HD - Same controller - only way to protect a boot and system paritions on NT
Duplexing - Mirrored on diff controller - allows split seeks
Split seeks - Allow the system to send read requests to whichever disk can respond first
*Cant withstand 2 simultaneous failures
-level 5 parity information uses the space that totals the size of one hardrive and is not counted in the total available user save
Fault Tolerance - Failed Drives
