1. RAID Non-Redundant (RAID Level 0) has the lowest cost of any RAID
offers the best performance since it never needs to update redundant information.
does not have the best performance.
without redundancy, any single disk failure will result in data loss.
widely used in environments where performance and capacity, rather than reliability, are the primary concerns.
Sequential blocks of data are written across multiple disks in stripes, as follows:

2. RAID Non-Redundant (RAID Level 0) Disk 0 Disk 1 Disk 2 Disk 3 Disk 4
Block 5
Block 10
Block 15
Block 20
Block 25
Block 1
Block 6
Block 11
Block 16
Block 21
Block 2
Block 7
Block 12
Block 17
Block 22
Block 3
Block 8
Block 13
Block 18
Block 23
Block 4
Block 9
Block 14
Block 19
Block 24

3. RAID Mirrored (RAID Level 1)
uses twice as many disks as non-redundant disk array
whenever data is written to a disk the same data is also written to a redundant disk
data can be retrieved from the disk with the shorter queuing, seek and rotational delays
disk fails, the other copy is used to service requests
requently used in database applications where availability and transaction time are more important than storage efficiency

4. RAID (RAID Level 2) Disk 0 Disk 1 Block 1 Block 2 Block 3 Block 4

5. RAID Bit interleaved array (RAID Level 2)
similar to ECC (error correcting code)
n+k disks, where k is the number of disks need to store an error correcting code for redundancy
dedicated ECC disks
expensive and uncommon
since modern disk drives contain their own internal ECC, RAID 2 is not a practical disk array scheme

6. RAID (RAID Level 2) Disk 0 Disk 1 ECC Disk 6 ECC Disk 7 . . . Bit1